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DOI: 10.1037/13937-006 APA Handbook of Behavior Analysis: Vol. 1. Methods and Principles, G. J. Madden (Editor-in-Chief) Copyright © 2013 by the American Psychological Association. All rights reserved.
C h a P t e r 6
OBSErvAtIOn And MEASurEMEnt In BEhAvIOr AnAlySIS
Raymond G. Miltenberger and Timothy M. Weil
You can observe a lot by watching. —Yogi Berra, circa 1964
Throughout its history, behavior analysis has focused on building an inductive science that uses behavioral observation techniques to identify func- tional behavior–environment relations such that alteration of these relations may result in behavior change that is scientifically, and often socially, meaningful. Measuring behavior–environment rela- tions in accurate and reliable ways is thus an inte- gral tool in the process of analyzing and changing behavior. Observable behavior has formal properties or dimensions that can be measured. These behav- ioral dimensions include frequency, intensity, dura- tion, and latency (e.g., Bailey & Burch, 2002; Miltenberger, 2012). Each of these dimensions affords the observer the opportunity to measure changes in level, trend, and variability when altera- tions of environmental variables occur naturally or are manipulated under various programmed conditions.
Observation and measurement of behavior may take many forms and involve a variety of techniques across practically any setting. In this chapter, we discuss observation and measurement in the field of behavior analysis with a focus on identifying and measuring the target behavior, logistics of observa- tion, recording procedures and devices, reactivity, interobserver agreement (IOA), and ethical consid- erations. The information discussed in this chapter is relevant to both research and practice in behavior analysis because observation and measurement of behavior is central to both endeavors.
BEHAVIOR
Regardless of whether the purpose of investigation is research or practice, it is first necessary to define behavior. Many authors define behavior in slightly different terms; however, each stresses an individu- al’s action or movement. According to Miltenberger (2012), behavior involves the actions of individuals, what people say and do. Malott and Trojan-Suarez (2004) suggested that behavior is anything a dead man cannot do, again suggesting that behavior con- sists of action or movement. Cooper, Heron, and Heward (2007) said that “behavior is the activity of living organisms. Human behavior is everything people do including how they move and what they say, think, and feel” (p. 25). Finally, Johnston and Pennypacker (1993) stated that behavior
is that portion of an organism’s interac- tion with its environment that is char- acterized by detectable displacement in space through time of some part of the organism and that results in a measurable change in at least one aspect of the envi- ronment. (p. 23)
These definitions of behavior are rooted in the tradi- tional characterization of an operant as observable action or movement that has some subsequent effect on (operates on) the environment (Johnston & Pennypacker, 1993, p. 25). Although the Cooper et al. definition of behavior includes thinking and feeling, these actions are nonetheless those of an individual that can be observed and recorded. Therefore, in this chapter we focus on observation and measurement of
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behavior that can be detected, and thus recorded, by an observer. In some cases, the observer may be the individual engaging in the behavior.
SELECTING AND DEFINING TARGET BEHAVIOR
The first step in developing a plan for observing and recording behavior is to select and then define appropriate target behavior.
Selecting Target Behavior Target behavior can be selected for a variety of over- lapping reasons (see Kazdin, 2010). It may be useful but arbitrary; representative of a broader class of operants; the focus of intervention or educational efforts that occur in a particular setting (e.g., aca- demic performance in a school setting); chosen because it causes impairment in some area of func- tioning for the individual; of particular concern to the individual or significant others who seek to change the behavior; or chosen because it will pre- vent the development of future problems (e.g., the promotion of safety skills to prevent injury). When selecting target behavior, three general categories are considered: behavioral deficits, behavioral excesses, and problems of stimulus control. Behav- ioral deficits are behaviors that need to increase, such as desirable communicative responses for a child with autism who has limited language (e.g., Sundberg & Michael, 2001). Behavioral excesses are behaviors that need to decrease, such as self- injurious or aggressive behavior emitted by an indi- vidual with intellectual disability (e.g., Lerman, Iwata, Smith, & Vollmer, 1994). Problems of stimulus con- trol are present when behaviors occur, but not at the appropriate time or place or in the appropriate con- text. For example, a child may learn to engage in a safety skill during training but fail to use it when the opportunity arises in the natural environment (e.g., Gatheridge et al., 2004; Himle, Miltenberger, Fless- ner, & Gatheridge, 2004). Likewise, a child with autism may learn to label an object but be unable to ask for the same object (e.g., failure of tact-to-mand transfer; Wallace, Iwata, & Hanley, 2006). Identify- ing developmentally appropriate topographies and levels of behavior is also important when selecting
the target behavior. For example, in research on stuttering, Wagaman, Miltenberger, and Arndorfer (1993) chose a criterion of 3% or fewer stuttered words as an indication of treatment success on the basis of research showing that as many as 3% of the words spoken by typical speakers were dysfluent.
A guiding factor in the selection of a target behavior in applied work is its social significance (Baer, Wolf, & Risley, 1968). Behavior is targeted that will increase the client’s meaningful and effec- tive interactions with the environment. One index of social significance is the assessment of the social validity of the targeted behavior (Wolf, 1978). According to Wolf (1978), one of the three levels of social validity is the degree to which society vali- dates the social significance of the goals of a behav- ior change procedure. In this regard, the important question posed by Wolf is, “Are the specific behav- ioral goals really what society wants?” (p. 207). In practice, assessment of the social validity of a target behavior or goal involves asking consumers for feed- back on what behavior should be addressed, in what order, and to what extent. Of course, the target behavior selected in this way may possibly have some secondary gain or benefit for the person pro- viding the report and thus may or may not be in the client’s best interest. The behavior analyst must be aware of this possibility and decide with the client, client surrogates, treatment team members, or some or all of these on the target behavior that best serves the client’s interests.
Although behavior analysts are interested in the behavior of clients or research participants, they are also interested in the behavior of the implementers carrying out behavior-analytic procedures. The degree to which individuals implement assessment and treatment procedures as planned is referred to as implementation fidelity, procedural fidelity, or treat- ment integrity (e.g., Gresham, Gansle, & Noell, 1993; Peterson, Homer, & Wonderlich, 1982). Implementation fidelity is important because higher fidelity is associated with better treatment outcomes (e.g., DiGennaro, Martens, & Kleinmann, 2007; DiGennaro, Martens, & McIntyre, 2005; DiGennaro- Reed, Codding, Catania, & Maguire, 2010; Plavnick, Ferreri, & Maupin, 2010). Implementation fidelity is assessed by observing and recording the behavior
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of the implementers as they observe and record the behavior of the clients or research participants and as the implementers carry out intervention proce- dures. Everything discussed in this chapter applies not only to observing and recording the behavior of clients or research participants, but also to measur- ing the behavior of the implementers.
Defining the Target Behavior The target behavior should be defined in terms that are objective, clear, and complete (Kazdin, 2010). A behavioral definition must include active verbs describing the individual’s actions, that is, the topog- raphy or form of the action being observed. Some behavioral definitions may also include the environ- mental events that precede (antecedents) or follow (consequences) the behavior. Behavioral definitions cannot include category labels (e.g., aggression) or appeal to internal states or characteristics (e.g., strong willed) but rather must identify the topogra- phy of the behavior. A behavioral definition should be easy to read and should suffice as a starting point for the observer to engage in data collection. Once a
behavior analyst begins to observe instances of the behavior, the behavioral definition may be modified on the basis of those observations. Some examples of target behavior definitions used in behavior-analytic research are shown in Table 6.1. Note the precise descriptions of behavior in these examples and the inclusion of the appropriate context for the behavior (e.g., unscripted verbalizations are “verbalizations that were not modeled in the video script but were appropriate to the context of the toy”) or the neces- sary timing of the behavior in relation to other events (e.g., an acceptance occurs when “the child’s mouth opened . . . within 3 seconds after the food item was held within 1 inch of the mouth”).
LOGISTICS OF OBSERVATION
Once the target behavior is identified and defined, the time and place of observation must be deter- mined and the observers identified. These logistics of observation are not insignificant, because the choices of observation periods and observers will determine the quality of the data derived from the observations.
TABLE 6.1
Examples of Target Behavior Definitions From Published Articles Involving Behavior Analytic Assessment and Treatment
Label Definition Citation
Empathy “A contextually appropriate response to a display of affect by a doll, puppet, or person that contained motor and vocal components (in any order) and began within 3 s of the end of the display.” (p. 20)
Schrandt, Townsend, and Poulson (2009)
Acceptance “The child’s mouth opened so that the spoon or piece of food could be delivered within 3 s after the food item was held within 1 in. of the mouth.” (p. 329)
Riordan, Iwata, Finney, Wohl, and Stanley (1984)
Expulsion “Any amount of food (that had been in the mouth) was visible outside the mouth (Joan only) or outside the lip and chin area (Nancy, Jerry, Holly) prior to presentation of the next bite.” (p. 329)
Riordan et al. (1984)
Activity engagement “Facial orientation toward activity materials, appropriate use of activity materials, or comments related to the activity.” (p. 178)
Mace et al. (2009)
Compliance “The child independently completing or initiating the activity described in the instruction within 10 s.” (p. 535)
Wilder, Zonneveld, Harris, Marcus, and Reagan (2007)
Unscripted verbalizations “Verbalizations that were not modeled in the video script but were appropriate to the context of the toy [that was present].” (p. 47)
MacDonald, Sacramone, Mansfield, Wiltz, and Ahern (2009)
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Time and Place of Observations Observation periods (the time and place chosen for observation) should be scheduled when the target behavior is most likely to occur (or, in the case of behavioral deficits, when the target behavior should be occurring but is not). In some cases, the target behavior occurs mostly or exclusively in the context of specific events (e.g., behavioral acquisi- tion training in academic sessions or athletic perfor- mance), and therefore, observation sessions have to occur at those times. A behavior analyst, however, may be interested in measuring the target behavior in naturalistic settings in which the behavior is, for the most part, free of temporal constraints. In these instances, it is possible to interview the client and significant people to narrow the observation win- dow. In addition, it may be valuable to validate the reports by collecting initial data on the occurrence of the target behavior. For instance, scatterplot assessments, which identify at half-hour intervals throughout the day whether the behavior did not occur, occurred once, or occurred multiple times, may help identify the best time to schedule the observation period (Touchette, Macdonald, & Langer, 1985). In instances in which reports on the occurrence of the target behavior are not available or when the reports are not descriptive enough, the behavior analyst should err on the side of caution and conduct a scatterplot assessment or other initial observations to narrow the observation window.
Identifying the times at which the target behavior is most likely to occur is desirable to capture the greatest number of instances. The rationale for observing and recording as many instances of the behavior as possible rests with evaluation of func- tion during assessment and analysis of the effects of the independent variable during intervention. When it is not possible to observe enough instances of the behavior across a number of observation periods to establish clear relations between the behavior and specific antecedents and consequences, treatment implementation may be delayed. With behavior that occurs at a lower rate, a longer time frame of obser- vation may be necessary to establish functional relations.
Although a delay to intervention after a baseline may be acceptable in some situations, in others it
could be undesirable or unacceptable for the client or significant others, such as teachers or parents. Such delays can sometimes be circumvented by structuring observations in an analog setting to eval- uate the effects of likely antecedent and consequent stimuli with the objective of evoking the target behavior. Alternatively, samples of the behavior might be collected in the natural environment at various times to provide a sufficient baseline that would allow making an accurate assessment of func- tion, deciding on an appropriate intervention, or both. Circumstances such as availability of observers and the client’s availability must also be considered.
A final consideration in preparing to make obser- vations is to select a placement within the observa- tion environment that permits a full view of the person and the behavior of interest while at the same time minimizing disruptions to the client or others in the environment. In addition, when col- lecting IOA data, it is important for both observers to see the same events from similar angles and dis- tances but simultaneously maintain their status as independent observers. Depending on the character- istics of the setting, issues may arise, such as walls or columns that impede seeing the behavior and interruptions from staff or other individuals. Disrup- tions in the environment are also a concern. For example, children in elementary school classrooms are notorious for approaching and interacting with an adult while he or she is observing and recording the target behavior. In addition, if the target child is identified, the other children may cause disruptions by talking to the target child or behaving in other- wise disruptive ways. Any disruption should be recorded so that it can be considered in accounting for variability in the data.
Selecting Observers Most behavioral observations in research and prac- tice are conducted by trained observers. Trained observers may not be needed in some laboratory set- tings in which permanent products are produced or equipment records the behavior automatically. However, in applied settings, individuals conducting behavioral observations must see the behavior as it occurs so data can be collected onsite or recorded for review at a later time. Individuals who could
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conduct behavioral observations in the same setting as the client include participant observers (individu- als who are typically present in the environment), nonparticipant observers (data collectors who are external to the typical workings of the environ- ment), or the client whose behavior is being observed (self-monitoring).
Participant observers. According to Hayes, Barlow, and Nelson-Gray (1999), participant observ- ers may be used in situations in which a significant other or other responsible party in the setting (e.g., parent, teacher) is available (and trained) to col- lect data. The primary advantage of including these individuals as observers is that they are already in the environment, which eliminates the potential logistical problems of scheduling nonparticipant observers. In addition, the likelihood of the child or student showing reactivity to observation is less- ened because the person being observed is likely to have habituated to the participant observer’s pres- ence over time. A limitation when using participant observers is that the observers may not have time to conduct observations because of their other respon- sibilities in the setting.
One factor to consider when arranging partici- pant observation (and nonparticipant observation) is the possibility of surreptitious observation. With surreptitious observation, the participant observer would not announce or otherwise cue the partici- pant to the fact that a particular observation session is taking place (e.g., Mowery, Miltenberger, & Weil, 2010). For example, in Mowery et al. (2010), gradu- ate students were present in a group home setting to record staff behavior. However, the staff members were told that the students were there to observe and record client behavior as part of a class project (this deception was approved by the institutional review board, and participants were later debriefed). Surreptitious observation leads to less reactivity in the person being observed. For surreptitious obser- vation to occur ethically, the client or participant must consent to observation with the knowledge that he or she will not be told, and may not be aware of, the exact time and place of observation (e.g., Wright & Miltenberger, 1987). The exception would be when a parent or guardian gives consent
for surreptitious observation of a child or a researcher gets institutional review board approval for deception and later debriefs the participants.
Nonparticipant observers. When it is either impossible or undesirable to involve a participant observer, nonparticipant observers who are not part of the typical environment are used. For instance, observations in school settings may require that an observer sit in an unobtrusive area of the classroom and conduct observations of the child at various times of the day. Three challenges of having non- participant observers involved in data collection are access, scheduling, and cost. Because observations tend to occur while clients are involved in social set- tings, it may not be permissible to observe because of the potential for disruption or for reasons of confidentiality. In the latter case, when conducting observations of the behavior of a single individual in a group setting such as a classroom, it is typical to require consent of all students in the group because all are present during the observation. This is espe- cially true when observations of minors occur.
Because observation periods may be relatively short (especially in the context of research), it may also be difficult to schedule an observer several times a day or week to collect data for only 15 to 60 minutes. In addition, the client’s schedule may restrict when observation may occur. Finally, a sig- nificant cost may be associated with the inclusion of skilled data collectors who may need to be hired to fulfill this role. Circumventing excessive costs is possible, however, if student interns or other staff already at the site are available. In addition to the monetary cost of the observers, there is cost in terms of time and effort to train the observers and conduct checks for IOA to ensure consistency in the data collected.
Self-monitoring. When the target behavior occurs in the absence of others, it may be useful to have cli- ents observe and record their own behavior. When asking clients to record their own behavior, it is nec- essary to train them as you would train any observer. Although there are examples of research using data gathered through self-monitoring (e.g., marijuana use [Twohig, Shoenberger, & Hayes, 2007]; disrup- tive outbursts during athletic performances [Allen,
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1998]; physical activity levels [Van Wormer, 2004]; binge eating [Stickney & Miltenberger, 1999]), self-monitoring is less desirable than observation by another individual because it may be unreli- able. If the target behavior occurs in the absence of others, then IOA cannot be assessed. For example, Bosch, Miltenberger, Gross, Knudson, and Brower- Breitweiser (2008) used self-monitoring to collect information on instances of binge eating by young women but could not collect IOA data because binge eating occurred only when the individual was alone.
Self-monitoring is best used when it can be com- bined with periodic independent observations to assess IOA. Independent observations occur when a second observer records the same behavior at the same time but has no knowledge of the other observer’s recording. Thus, the recording of both observers is under the stimulus control of the behav- ior being observed and is not influenced by the recording behavior of the other observer. When IOA is high, it might indicate that self-monitoring is being conducted with fidelity. It is possible, how- ever, that self-monitoring is conducted with fidelity only under the conditions of another observer being present, but not when the client is alone or away from the other observer. In some instances, it is pos- sible to collect secondary data or product measures that can be used to verify self-monitoring. For instance, researchers measured expired carbon mon- oxide samples in smoking cessation research (Brown et al., 2008; Raiff, Faix, Turturici, & Dallery, 2010) and tested urine samples in research on substance abuse (Hayes et al., 2004; Wong et al., 2003).
Given the potential unreliability of self-monitoring, taking steps to produce the most accurate data pos- sible through self-monitoring is important. Such steps might include making a data sheet or data col- lection device as easy to use as possible, tying data collection to specific times or specific activities to cue the client to record his or her behavior, having other people in the client’s environment cue the cli- ent to conduct self-monitoring, checking with the client frequently by phone or e-mail to see whether self-monitoring is occurring, having the client sub- mit data daily via e-mail or text message, and prais- ing the client for reporting data rather than for the level of the behavior to avoid influencing the data.
Even with these procedures in place, clients may still engage in data collection with poor fidelity or make up data in an attempt to please the therapist or researcher. Therefore, self-monitoring that lacks verification should be avoided as a form of data col- lection whenever possible.
Training Observers Adequate observer training is necessary to have con- fidence in the data. Observing and recording behav- ior can be a complex endeavor in which the observer must record, simultaneously or in rapid order, a number of response classes following a specific pro- tocol, often while attending to timing cues (see Sam- pling Procedures section). Finally, following this routine session after session may lead to boredom and set the occasion for observer drift. Observer drift is the loosening of the observer’s adherence to the behavioral definitions that are used to identify the behavioral topographies to be recorded, a decrease in attending to specific features of the data collec- tion system, or both. When observer drift occurs, the accuracy and reliability of the data suffer, and faulty decisions or conclusions may result (see Kazdin, 1977).
One way to train observers is to use behavior skills training (Miltenberger, 2012), which involves providing instructions and modeling, having the observer rehearse the observation and recording procedures, and providing feedback immediately after the performance. Such training occurs first with simulated occurrences of the target behavior in the training setting and then with actual occurrences of the target behavior in the natural environment. Subsequent booster sessions can be conducted in which the necessary training components are used to correct problems. To maintain adequate data col- lection, it is necessary to reinforce accurate data collection and detect and correct errors that occur.
Several factors can influence the fidelity of data col- lection (Kazdin, 1977). These include the quality of initial training, consequences delivered for the target behavior (Harris & Ciminero, 1978), feedback from a supervisor for accurate data collection (Mozingo, Smith, Riordan, Reiss, & Bailey, 2006), complexity and predictability of the behavior being observed (Mash & McElwee, 1974), and the mere presence of a
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supervisor (Mozingo et al., 2006). With these factors in mind, strong initial training and periodic assess- ment and retraining of observers are recommended for participant observers, nonparticipant observers, and individuals engaging in self-monitoring.
RECORDING PROCEDURES
The procedures available for collecting data on tar- geted behavior are categorized as continuous record- ing procedures, sampling procedures, and product recording.
Continuous Recording Continuous recording (also called event recording) procedures involve observation and recording of each behavioral event as it occurs during the obser- vation period. Continuous recording will produce the most precise measure of the behavior because every occurrence is recorded. However, continuous recording is also the most laborious method because the observer must have constant contact with the participant’s behavior throughout the observation period. As with all forms of data collection, continu- ous recording requires the behavior analyst to first identify the dimensions on which to focus. Observ- ers are recommended to initially collect data on multiple dimensions of the behavior (e.g., frequency and duration) to identify the most relevant dimen- sions and to then wean over the course of observa- tions as the analysis identifies the most important dimensions. For example, in a classroom situation involving academic performance, it may be useful to count the number of math problems completed cor- rectly, latency to initiate the task (and each prob- lem), and the time spent on each problem. If after several observations the observer finds that it takes a while for the child to initiate the task, resulting in a low number of problems completed, focusing on measuring latency to initiate the task and fre- quency of correct responses may be useful. Next, we describe data collection procedures related to differ- ent dimensions of behavior. Although we discuss the procedures separately, various combinations of these procedures may produce important data for analysis that would not be apparent with a focus on a single procedure.
Frequency. Perhaps the most common form of continuous recording is frequency recording: count- ing the number of occurrences of the target behavior in the observation period (Mozingo et al., 2006). Frequency recording is most appropriate when the behavior occurs in discrete units with fairly consistent durations. In frequency recording, each occurrence of the target behavior (defined by the onset and offset of the behavior) is recorded in the observation period. Frequency data may be reported as total frequency—number of responses per obser- vation session—or converted to rate—number of responses per unit of time (e.g., responses per min- ute). Total frequency would only be reported if the observation periods were of the same duration over time. The advantage of reporting rate is that the measure is equivalent across observation periods of different durations.
Frequency recording requires the identification of a clear onset and offset of the target behavior so each instance can be counted. It has been used with a wide range of target behavior when the number of responses is the most important characteristic of the behavior. Examples include recording the frequency of tics (Miltenberger, Woods, & Himle, 2007), greet- ings (Therrien, Wilder, Rodriguez, & Wine, 2005), requests (Marckel, Neef, & Ferreri, 2006), and math- ematics problems completed (Mayfield & Vollmer, 2007). When it is difficult to discriminate the onset or offset of the behavior or the behavior occurs at high rates such that instances of the behavior cannot be counted accurately (e.g., high-frequency tics or stereotypic behavior), a behavior sampling procedure (i.e., interval or time-sample recording; see below) is a more appropriate recording procedure. As we elab- orate on later, in sampling procedures the behavior is recorded as occurring or not occurring within con- secutive or nonconsecutive intervals of time, but individual responses are not counted.
Four additional methods of recording frequency are frequency-within-interval recording, real-time recording, cumulative frequency, and percentage of opportunities. Each method has advantages over a straight frequency count.
Frequency-within-interval recording. One limi- tation of frequency recording is that it does not
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provide information on the timing of the responses in the observation period. With frequency-within- interval recording, the frequency of the behavior is recorded within consecutive intervals of time to indicate when the behavior occurred within the observation period. To conduct frequency-within- interval recording, the data sheet is divided into con- secutive intervals, a timing device cues the observer to the appropriate interval, and the observer records each occurrence of the behavior in the appropriate interval. By providing information on the number of responses and the timing of responses, more precise measures of IOA can be calculated.
Real-time recording. Combining features of fre- quency and duration procedures, real-time recording also allows the researcher to collect information on the temporal distribution of the target behavior over the course of an observation period (Kahng & Iwata, 1998; Miltenberger, Rapp, & Long, 1999). Through use of either video playback or computers in real time, it is possible to record the exact time of onset and offset of each occurrence of the behavior. For discrete momentary responses that occur for 1 second or less, the onset and offset are recorded in the same second.
Real-time recording is especially valuable when conducting within-session analysis of behavioral sequences or antecedent–behavior–consequence rela- tions. Borrero and Borrero (2008) conducted real- time observations that included the recording of both target behavior and precursor behavior or events related to the target behavior. These data were then used to construct a moment-to-moment analysis (lag- sequential analysis) that provided probability values for the occurrence of the precursor given the target behavior and of the target behavior given the precur- sor. The probability of a precursor reliably increased approximately 1 second before the emission of the target behavior. In addition, the probability of the tar- get behavior was greatest within 1 second after the precursor behavior or event. The real-time analysis suggested that the precursor behavior or event was a reliable predictor of the target behavior. Additional analysis showed that both the precursor behavior and the target behavior served the same function (e.g., both led to escape from demands).
Cumulative frequency. The origins of measuring operant behavior involved the use of an electrome- chanical data recording procedure that was designed to record instances of behavior cumulatively across time (Skinner, 1956). Each response produced an uptick in the data path as the pen moved across the paper and the paper revolved around a drum. The original paper records of this recording were only about 6 inches wide, and thus the pen used to record responses would, on reaching the top of the paper, reset to the bottom of the paper and continue recording the responses. Increasing slopes indicated higher response rates; horizontal lines indicated an absence of the response.
This apparatus for the automatic recording of cumulative frequencies is no longer used, but the usefulness of cumulative response measures persists. In cumulative frequency graphs, data are displayed as a function of time across the x-axis and cumula- tive frequency along the y-axis. The frequency of responses that occur in a given time period is added to the frequency in the previous time period. Thus, data presented in a cumulative record must either maintain at a particular level (no new responses) or increase (new responses) across time but never decrease. The use of cumulative frequency plots allows one to assess frequency and temporal pat- terns of responding.
Percentage of opportunities. In some cases, recording the occurrence of a response in relation to a specific event or response opportunity is use- ful. In such cases, the percentage of opportunities with correct responses is more important than the number of responses that occurred. For example, in recording compliance with adult requests, the per- centage of requests to which the child responds cor- rectly is more important than the number of correct responses. Ten instances of compliance are desirable if 10 opportunities occur. However, 10 instances of compliance are much less desirable in relation to 30 opportunities. Other examples include the percentage of math problems completed correctly, percentage of free throws made in a basketball game, percentage of signals detected on a radar screen dur- ing a training exercise, and percentage of trials in which an item is labeled correctly during language
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training. Considering that the number of opportuni- ties might vary in each of these cases, the percentage of opportunities is a more sensitive measure of the behavior than a simple frequency count or a rate measure.
When a percentage-of-opportunities measure is used, reporting the number of opportunities as well as the percentage of correct responses is important. If the number of opportunities is substantively dif- ferent across observations, it may affect the variabil- ity of the data and the interpretation of the results. For instance, if on one occasion a child is provided with 10 spelling words and spells eight correctly, the result is 80% correct. The next day, if the two words spelled incorrectly are retested and the child spells one of the words correctly, the second performance result is 50% correct. These data are not comparable because the number of opportunities varied greatly, and inappropriate conclusions could be drawn from the results if only percentages were reported. In these instances, providing an indicator of the num- ber of opportunities to respond in the graphical rep- resentation of the data will assist the reader in interpreting the results.
Duration. When each response lasts for an extended period of time or does not lend itself to a frequency count (e.g., as in behavior such as read- ing or play), it may be useful to record the duration of the behavior, that is, the time from its onset to its offset. Duration recording is desirable when the most important aspect of the behavior is the length of time for which it occurs. For example, if the interest were in sustained performance or time on task, duration recording is appropriate. If classroom teachers are concerned with sustained engagement in academic activities, the observer would identify the length of time that engagement is desired (such as in reading) and collect data on the duration of engagement to identify any discrepancy between the target duration and actual performance. Once a discrepancy is determined to exist, programming for successively longer durations could be initiated.
Other situations involve a combination of dura- tion and frequency recording, as when the goal is to decrease a young child’s tantrum behavior. If tan- trums occur multiple times per day and each tantrum
continues for a number of minutes, recording both frequency and duration will reveal whether tan- trums are occurring less often and occurring for shorter periods of time after intervention.
Finally, many types of behavior targeted in applied work do not lend themselves readily to fre- quency counts because they consist of (a) responses that occur rapidly and repetitively over extended periods of time (such as stereotypic behavior), (b) complexes of discrete responses integrated into chains or other higher order units, or (c) both. For rapid, repetitive responses, for which each onset and offset is not easily discriminated, a duration measure can be used. In such cases, a time period in which the behavior is absent can help the observer discrim- inate the end of one episode and the start of the next. For target behavior consisting of multiple compo- nent behaviors, the target behavior might be defined as the entire chain, and a duration measure would then consist of recording the time from the onset of the first response in the chain to the offset of the last response in the chain. Finally, in some instances duration is used to measure a behavior with multiple component responses when it does not make sense to reduce the behavior to a frequency count of its component responses. For example, duration of play would be of greater interest to a parent trying to increase a child’s play time than would a frequency count of the number of steps the child traveled across the playground, went up and down a slide, or moved back and forth on a swing.
Latency. Latency is the length of time from the pre- sentation of a discriminative stimulus to the initia- tion of the behavior. Latency is of interest when the speed of initiation of the behavior is an important feature. For example, latency is the time from the sound of the starter’s pistol to the sprinter’s move- ment off the starting blocks, the time it takes for a child to initiate a task after the teacher’s request, or the time it takes the wait staff at a restaurant to respond once a customer is seated.
When working with a child who does not com- plete math problems in the allotted time, for exam- ple, latency indicates how long it takes the child to initiate the task. By contrast, duration assesses how long it takes the child to complete each problem
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once he or she starts working on it. Depending on the child and the circumstance, one or both dimen- sions may be an important focus of assessment and intervention.
Magnitude. On occasion, evaluating the magni- tude or intensity of behavior is useful. One example of response magnitude is the force exerted (e.g., muscle flexion), and another is the loudness of a verbal response (as measured in decibels). Although decreases in frequency, and perhaps duration, of undesirable behaviors such as tantrums or self- injury are important, a reduction in magnitude may be an important initial goal. In some cases, reduc- tions in magnitude may be observed before substan- tial decreases occur on other dimensions, such as frequency and duration. Alternatively, magnitude may increase temporarily during an extinction burst before the behavior decreases in frequency, duration, or intensity.
Recording magnitude may be valuable when considering recovery from an accident or injury such as a knee injury for a football player. Measure- ment would pertain to the ability of the affected muscles to exert force after rehabilitation. In these situations, recording magnitude tends to require equipment such as that used by physical therapists to evaluate force.
Direct observation of response magnitude may not always measure force, however. Observers can use intensity rating scales to evaluate the magnitude of a response. For instance, given a scale ranging from 1 to 10, a teacher may rate the intensity of each occurrence of an undesirable behavior. In using rat- ing scales, it is important to anchor the points within the scale such that two observers can agree on the level of intensity given a variety of occur- rences of the behavior (e.g., 1 = mild whining, 10 = loud screaming, throwing items, and head banging). Although anchoring categories on a scale is consid- ered valuable to decrease the variability in respond- ing across observers, the literature is not clear as to how many individual categories need be defined (Pedhazur & Schmelkin, 1991). Another example in which magnitude can be measured with a rating scale is the intensity of a fear response (Milten- berger, Wright, & Fuqua, 1986; Twohig, Masuda,
Varra, & Hayes, 2005) or other emotional responses (Stickney & Miltenberger, 1999). In general, inten- sity rating scales present issues of both reliability and validity because the ratings that might be assigned to specific instances of behavior may be ambiguous; this is especially true when rating fear or emotional responses because the magnitude of these behaviors can be rated only by the individual engaging in the behavior.
Sampling Procedures It may not always be possible to collect adequate information on the target behavior using continuous recording procedures. When the onset and offset of each instance of the behavior cannot be identified, continuous recording is not possible. Likewise, the constraints imposed by some environments, some target behaviors, or some observers may make con- tinuous recording impossible. For example, the person exhibiting the target behavior might not be continuously in sight of the observer, the target behavior might occur almost exclusively when the individual is alone, or the observer might have other responsibilities that compete with observation. In these instances, it may be desirable, and necessary, to collect samples of the behavior that provide an estimate of the behavior’s true level. Behavior- sampling procedures include interval recording and time-sample recording. In both procedures, the observation period is divided into smaller units of time, and the observer records whether the behavior occurred in each interval.
Interval recording. Interval recording involves dividing the observation period into equal consecu- tive intervals and recording whether the behavior occurred in each. Interval recording is different than frequency recording or frequency-within- interval recording in that an interval is scored once regardless of whether a single instance or multiple instances of a behavior occurred during the interval. In behavior analysis research, intervals are usually short—typically 10 to 15 seconds (DiGennaro et al., 2007; Mace et al., 2009). Short intervals (usually less than 20 seconds) are valuable when behavior occurs at moderate to high frequencies or when multiple topographies of behavior are recorded.
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Valuable too are shorter intervals when temporal correlations may yield information on antecedent events and potential maintaining consequences. When interested in the relation between the target behavior and antecedents and consequences, the observer records whether any of the three events occurred in each interval to examine the temporal patterns of the behavior and its potential controlling variables (e.g., Repp & Karsh, 1994). An additional condition under which shorter intervals are valuable is when an understanding of within-session tem- poral distribution of the behavior is necessary. For example, to determine whether self-injurious behav- ior is high in a functional analysis condition because of an extinction burst, the behavior analyst identi- fies whether more intervals were scored early in the session than later in the session (Vollmer, Marcus, Ringdahl, & Roane, 1995). Similar patterns could be discerned with cumulative frequency recording or real-time recording as well.
In some applied settings, however, intervals might be much longer—perhaps 15 or 30 minutes (Aikman & Garbutt, 2003)—when behavior occurs less frequently. Under these conditions, it may be difficult to draw useful correlations between ante- cedent and consequent events and the behavior as well as behavior–behavior relations. Such limita- tions notwithstanding, longer intervals are typically used for the convenience of data collectors (often participant observers) who can engage in other responsibilities and still collect data.
Typically, the observer has a data sheet with con- secutive intervals designated for recording, and dur- ing the observation period, the observer is prompted with auditory (through headphones so as to not dis- rupt the ongoing behavior of the observee) or tactile (vibration) cues delivered via a timing device to move from interval to interval while observing and recording the target behavior. As time passes, the observer records the occurrence of the target behav- ior in the appropriate interval; a blank interval indi- cates the nonoccurrence of the behavior in that interval. In some cases, a computer is used for data collection, and as the observer records the behavior, the software puts the data into the proper interval. At the end of the observation period, the number of intervals in which the behavior is observed is
divided by the number of observation intervals, and the result is reported as the percentage of intervals in which the behavior occurred. A similar process is used for time-sample recording (described in the next section).
The two types of interval recording procedures are partial-interval recording and whole-interval recording. In partial-interval recording, the observer records the occurrence of the target behavior if it occurred at any time within the interval. That is, the interval is scored if the target behavior occurred briefly in the interval or throughout the entire inter- val. Furthermore, if the onset of the behavior occurs in one interval and its offset occurs in the next, both intervals are scored (e.g., Meidinger et al., 2005).
In whole-interval recording, the interval is scored only if the target behavior occurred throughout the entire interval. Whole-interval recording is more useful with continuous behavior (e.g., play) than with discrete or quickly occurring behavior (e.g., a face slap). Typically, whole-interval recording is used when a behavior occurs over longer periods of time, as might be seen with noncompliant behavior or on-task behavior. For example, Athens, Vollmer, and St. Peter Pipkin (2007) recorded duration of on- task behavior in 3-second intervals only if the behavior was present for the entire interval.
Time-sample recording. In time-sample record- ing, the observation period is divided into intervals of time, but observation intervals are separated by periods without observation. Time-sample recording permits the observer to focus on other tasks when not observing the target behavior. For example, the observation period might be divided into 15-second intervals, but observation occurs only at the end of the interval. Likewise, an observation period might be divided into 30-minute intervals, but observa- tion and recording occur only in the last 5 minutes of every 30 minutes. These intervals can be equally divided, as when an observation occurs every 15 minutes, or variably divided to provide some flexi- bility for the observer (such as a teacher who cannot observe exactly on the quarter hour). The data are displayed as a percentage (the number of intervals with target behavior divided by the number of inter- vals of observation).
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For instance, if evaluating the extent of social interactions between adolescents on a wing of an inpatient psychiatric facility were desirable, con- ducting observations every 15 minutes might be possible. In this example, the observer would be engaged in a job-related activity and, when prompted by a timer, look up from his or her work, note whether the target behavior was occurring, and record the result. Data of this sort could identify which of the adolescents tend to engage in social interactions and the typical times at which social interactions are likely to occur. From this sampling approach, it is possible to refine the data collection process toward a more precise measure of behavior.
Interval and time-sample recording have benefits and limitations. The benefit of interval recording is that with consecutive observation intervals, no instance of the target behavior is missed during the observation period. The limitation, especially with shorter intervals, is that it requires the continu- ous attention of, and frequent recording by, the observer, making it difficult for the observer to engage in other activities during the observation period. A limitation of time-sample recording is that because observation intervals are separated by peri- ods without observation, some instances of the tar- get behavior may be missed during the observation period. However, a benefit is that the observer can engage in other activities during the periods between observation intervals, making the proce- dure more user friendly for participant observers such as teachers or parents.
Although interval and time-sample recording procedures are used widely in behavior-analytic research, some authors have cautioned that the results of these sampling procedures might not always correspond highly with data collected through continuous recording procedures in which every behavioral event is recorded (e.g., Rapp et al., 2007; Rapp, Colby-Dirksen, Michalski, Carroll, & Lindenberg, 2008). In summarizing the numerous studies that have compared interval and time- sample recording with continuous recording proce- dures, Rapp et al. (2008) concluded that interval recording tends to overestimate the duration of the behavior, time-sample procedures with small inter- vals tend to produce accurate estimates of duration,
and interval recording with small intervals tends to produce fairly accurate estimates of frequency. Although Rapp et al. provided several suggestions to guide decision making regarding the use of interval and time-sample procedures, they concluded by suggesting that small interval sizes in interval and time-sample procedures are likely to produce the best results.
Product Recording In some cases, the outcome or the product of the behavior may be of interest, either as a primary dependent variable or as a complement to direct observation of the behavior itself. When the behav- ior changes the physical environment, this product can be recorded as an index of the occurrence of the behavior. In some instances, collecting data on products is valuable because measuring the behavior directly may not be possible. For example, weight is measured in weight-loss programs because measur- ing the behavior that produces weight loss (i.e., diet and exercise) is usually not feasible. Examples of product recording may include number of academic problems completed or number of units assembled in a factory. In each case, the occurrence of the behavior is not observed directly; rather, the prod- ucts of the behavior are recorded as an indication of its occurrence. In such cases, a focus on the prod- ucts of behavior is easier and more efficient than recording the behavioral events as they occur. An important note in recording permanent products is that although the focus is on results, if the results fall short of expected quantity or quality, the focus can then turn to evaluation of the behavior involved in producing the products being measured (Daniels & Daniels, 2004).
Beyond measuring the production of tangible items, product recording can be used to measure the physical damage caused by a problem behavior. For example, self-injurious behavior can produce tissue damage such as bruises, lacerations, or other bodily injuries, and product recording could be used to assess the severity of these injuries. Iwata, Pace, Kissel, Nau, and Farber (1990) developed the Self- Injury Trauma Scale to quantify surface injury resulting from self-injurious behavior. Other exam- ples of this type of product recording include the
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assessment of the size of a bald area related to chronic hair pulling (Rapp, Miltenberger, & Long, 1998; Rapp, Miltenberger, Long, Elliott, & Lumley, 1998) or the length of fingernails as a measure of nail biting (Flessner et al., 2005; Long, Milten- berger, Ellingson, & Ott, 1999). Still other examples of product recording include a measure of weight or body mass index as an indication of changes in eat- ing (Donaldson & Normand, 2009; see also Young et al., 2006), measuring chemicals in urine samples as a measure of drug ingestion (Silverman et al., 2007), or weighing food before and after a feeding session to assess the amount of food consumed (Kerwin, Ahearn, Eicher, & Swearingin, 1998; Maglieri, DeLeon, Rodriguez-Catter, & Sevin, 2000; Patel, Piazza, Layer, Colemen, & Swartzwelder, 2005).
An advantage of product recording is that the observer does not have to be present to record the occurrence of the behavior (Miltenberger, 2012) because the product can be recorded at a more con- venient time after the behavior has occurred (e.g., at the end of the class period or after the shift in a fac- tory). A drawback of product recording, especially when used with a group of individuals, is that it might not be possible to determine which person engaged in the behavior that resulted in the product. Perhaps another student completed the academic problems or another worker helped produce the units in the factory (Jessup & Stahelski, 1999). Although product recording is valuable when the interest is in the tangible outcome of the behavior, there must be some way to determine which indi- vidual was responsible for the products being mea- sured (e.g., did the urine sample come from the client or someone else?). Another potential problem with some uses of product recording is that it may not identify the behavior that resulted in the prod- uct. For example, correct answers to math problems may have been produced by cheating, and weight loss may have been produced through self-induced vomiting rather than an increase in exercise or a reduction in calorie consumption.
Recording Devices Once the appropriate recording procedure has been chosen, the next step is to choose a recording device. Because the observer must record instances
of the behavior as they occur, the observer’s behav- ior must result in a product that can be used later for purposes of analysis. A recording device allows the observer to produce a permanent product from the observation session. The most commonly used recording device is a data sheet structured for the type of recording procedure being conducted. Figures 6.1, 6.2, and 6.3 show sample data sheets structured for frequency recording, duration record- ing, and interval recording, respectively.
Although data sheets are used most often for data collection, other recording devices, both low tech and high tech, can be used to record instances of the behavior. Several types of low-tech recording devices have been used, such as wrist counters for frequency recording (Lindsley, 1968) or stop watches for duration recording. Still other possibili- ties include activities as simple as moving beads from one side of a string to the other, placing a coin from one pocket to another, making small tears in a piece of paper, or making a hash mark on a piece of masking tape affixed to the recorder’s sleeve to record frequency (Miltenberger, 2012). In fact, it is feasible to record frequency with whatever may be available in the environment as long as the observer can produce a product that represents the occur- rence of the behavior.
Although recording on a data sheet is the most frequently used data collection process, with rapidly changing technologies there is a move to identify high-tech methods to streamline and automate data collection (Connell & Witt, 2004; Jackson & Dixon, 2007; Kahng & Iwata, 1998). In applied behavior analysis research, electronic devices such as a per- sonal digital assistant (Fogel, Miltenberger, Graves, & Koehler, 2010) or hand-held or laptop computers (Gravlee, Zenk, Woods, Rowe, & Schulz, 2006; Kahng & Iwata, 1998; Repp, Karsh, Felce, & Ludewig, 1989) are frequently used for data collec- tion. In addition, the use of bar codes and scanners (Saunders, Saunders, & Saunders, 1993) for data collection has been reported. With bar code scan- ners, an observer holds a small battery-powered scanning device and a sheet of paper with the bar codes ordered according to behavioral topography. When the target behavior is observed, the data col- lector scans the relevant bar code to record the
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occurrence of the behavior and the time within the observation period. The use of bar codes is, how- ever, only one of several ways to conduct electronic recording of behavior.
In one investigation evaluating a shaping proce- dure to increase the reach of a pole vaulter, a photo- electric beam was used to determine the height of the vaulter’s reach just after planting the pole for the
vault (Scott, Scott, & Goldwater, 1997). Another high-tech method of data collection involves soft- ware for cell phones. These software applications, colloquially referred to as apps, allow behavior ana- lysts to use the computing power of their phones for data collection. The advantages of this technol- ogy are numerous; however, the most obvious bene- fits are the use of a small, portable device that can
Duration Data Form
Child: James M. Start Date: 9/15/2010 Setting: Mathematics
Observer: R.M. Primary/Reliability
Instructions: First, indicate date of observation in the far left column. Second, identify the start time (onset) and the stop time (offset) for each occurrence of the behavior. Use more than one line if necessary.
Definition of behavior:_________________________________________________________
____________________________________________________________________________
Date Onset Offset Onset Offset Onset Offset Onset Offset DailyDuration
FIGURE 6.2. An example of a duration data sheet that provides information on the onset and offset of each occurrence of the behavior and the frequency of the behavior each day.
Frequency Data Form
Child: James M. Start Date: 9/15/2010 Setting: Mrs. Johnson’s Class
Observer: R.M. Primary/Reliability
Instructions: First, indicate date of observation in the far left column. Second, place a tick mark for each occurrence of behavior during the specified academic activity for that day.
Definition of behavior:_________________________________________________________
____________________________________________________________________________
Date CircleTime Mathematics Individual Reading
Social Studies Science Writing
Daily Total
FIGURE 6.1. Example of a daily frequency data sheet that involves a break- down of the frequency of the behavior by curricular areas in a general education classroom setting.
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facilitate any form of data collection mentioned thus far and the ability to graph the data. Finally, these graphs can be sent via text message to parents, teachers, or colleagues (Maher, 2009). Undoubtedly, as technology advances, even more high-tech data collection methods will emerge.
Reactivity of Observation A long-standing concern for behavioral researchers is how observation affects performance (e.g., Par- sons, 1974). Reactivity is the term used to describe changes in behavior resulting from the act of observ- ing and recording the behavior. Typically, when reactivity occurs, the behavior changes in the
desired direction (e.g., Brackett, Reid, & Green, 2007; Mowery et al., 2010). Several researchers have evaluated the effects of staff reactivity to observa- tions (Boyce & Geller, 2001; Brackett et al., 2007; Codding, Livanis, Pace, & Vaca, 2008; Mowery et al., 2010). Mowery et al. (2010) evaluated staff adherence to a protocol designed to increase the fre- quency of staff’s positive social initiations during lei- sure activities with adults with developmental disabilities. They evaluated the effects on staff behavior of having a supervisor absent or a supervi- sor present in the environment to determine whether reactivity to the supervisor’s presence would occur. Positive social interactions only
Interval Data Form
Child: James M. Date: 9/15/2010 Setting: Mathematics
Observer: R.M. Primary/Reliability
Instructions: Place a check mark in the appropriate column to reflect the events that occurred in each 10–s interval.
Definition of behavior:_________________________________________________________
____________________________________________________________________________
10-s Intervals
Demand Placed Aggression Attention Ignore Escape
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
FIGURE 6.3. An example of a 10-second interval data sheet (partial or whole) that provides information on the occurrence of the target behavior and probable antecedents and consequences. In this example, the hypothesis is that the aggressive behavior occurs after the delivery of a demand by the teacher. In addition, potential responses by the teacher to the problem behav- ior are included. When completed, this data sheet will provide information on the temporal relationship between teacher behavior and student problem behavior.
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occurred at acceptable levels when the supervisor was present, suggesting that reactivity is an impor- tant issue to consider in the valid assessment of staff performance.
Considering reactivity to observation in research or clinical settings is important because the target behavior may be influenced not only by the inter- vention but also by the act of observing. When responding comes under the stimulus control of an observer, the level of behavior in the presence of the observer is likely to be different than in the absence of the observer. Considering that most staff behavior must be performed in the absence of supervision, conducting observations without reactivity to obtain an accurate characterization of the behavior is important. There are a variety of ways in which to minimize reactivity. For instance, making observers a part of the regular environment for several ses- sions or weeks before actual data collection occurs may result in habituation to the presence of the observers. It is important to keep in mind that habit- uation to the observer is only likely to occur as long as the observer does not interact with the person being observed and no consequences are delivered by the observer or others who may be associated with the observer.
If the setting permits, reactivity may be avoided in other ways. Video monitoring devices mounted unobtrusively in the setting may be used. In instances in which the cameras can be seen by the person being observed, habituation to the presence of the camera is likely to occur in the absence of feedback or consequences contingent on perfor- mance (e.g., Rapp, Miltenberger, Long, et al., 1998). In addition, using an observation room equipped with a one-way observation window provides the observer an opportunity to conduct unannounced observations. If the use of an observation window is not possible, the use of confederates may be consid- ered. Although confederates are present in the set- ting to collect data (unobtrusively), a benign purpose for their presence other than data collection is provided to those being observed. That is, decep- tion is used to conceal the true purpose of the observers’ presence. As mentioned in the Mowery et al. (2010) study, confederates may be used to increase the chances that the data collected are
representative of typical levels (the level expected in the absence of observation). Confederates can be any variety of individuals such as a coworker, class- mate, spouse, or person external to the setting as seen in Mowery et al. (2010), in which observers were introduced as student social workers who were in the setting to observe individuals with intellectual disabilities.
In recent research on abduction prevention, chil- dren were observed without their knowledge to assess their safety skills as a confederate approached and attempted to lure them in a store setting (Beck & Miltenberger, 2009). Research on child safety skills training has demonstrated that children are more likely to respond correctly when they are aware of observation than when they are not aware of observation (Gatheridge et al., 2004; Himle, Miltenberger, Gatheridge, & Flessner, 2004). An important caveat is that the use of confederates may raise ethical concerns and should be approached cautiously. The use of video or other inconspicuous monitoring systems may present the same ethical concerns and thus should also be approached with caution. Prior approval is needed when using decep- tive covert observation. Additionally, for research purposes such covert observation must be approved by an institutional review board with appropriate debriefing afterward.
INTEROBSERVER AGREEMENT
Within research and practice in applied behavior analysis, accurate data collection is important (see Chapter 7, this volume). Accuracy refers to the extent to which the recorded level of the behavior matches the true level of the behavior (Cooper et al., 2007; Johnston & Pennypacker, 1993; Kazdin, 1977). To evaluate accuracy, a researcher must be able to obtain a measure of the true level of the behavior to compare with the measurement of the behavior produced by the observer. The difficulty arises in obtaining the true level of the behavior, as most recording is done by humans who must dis- criminate the occurrence of the behavior from non- occurrences (a stimulus–control problem). A “truer” level of the behavior may be obtained through mechanical means, but equipment also may fail
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on occasion and produce errors. Alternatively, automated recording devices may fail to register responses that vary slightly in topography or loca- tion. Thus, knowing the true level of the behavior with certainty is impossible, and therefore accuracy is not measured in behavioral research.
Instead, behavior analysts train observers so that the data they collect are in agreement with those collected by another observer who has received training in recording the target behavior. Although measuring agreement between observers provides no information about the accuracy of either set of observations, it does improve the believability of the data. That is, when two independent observers agree on every occurrence and nonoccurrence of behavior, one has more confidence that they are using the same definition of the target behavior, observing and recording the same responses, and marking the form correctly (Miltenberger, 2012). If a valid definition of the behavior of interest is being used, then high agreement scores increase the belief that the behav- ior has been recorded accurately; although, again, accuracy has not been measured.
A frequently used measure of agreement between observers is simply the percentage of observations that agree, a measure commonly referred to as IOA. IOA is calculated by dividing the number of agree- ments (both observers recorded the occurrence or nonoccurrence of the behavior) by the number of agreements plus disagreements (one observer recorded the occurrence of the behavior and the other recorded the nonoccurrence of the behavior) and multiplying the quotient by 100. For an ade- quate assessment of IOA, two independent data col- lectors are recommended to be present during at least one third of all observation sessions across all participants and phases of a clinical intervention or research study (Cooper et al., 2007). This level of IOA assessment (one third of sessions) is an arbi- trary number, and efforts to maximize the number of assessments that produce strong percentages of agreement should result in greater confidence in the data.
Cooper et al. (2007) suggested that research studies maintain 90% or higher IOA but agreed that 80% or higher may be acceptable under some circumstances. Kazdin (2010) offered a different
perspective on the acceptable level of IOA and sug- gested that the
level of agreement that is acceptable is one that indicates to the researcher that the observers are sufficiently consistent in their recording of the behavior, that the behaviors are adequately defined, and that the measures will be sensitive to change in the client’s performance over time. (p. 118)
Kazdin suggested that the number and complexity of behaviors being recorded, possible sources of bias, expected level of change in the behavior, and method of computing IOA are all considerations in deciding on an acceptable level of IOA. For example, if small changes in behavior are likely with the inter- vention, then higher IOA would be demanded. However, if larger changes are expected, then lower levels of IOA might be tolerated. The bottom line is that behavior analysts should strive for levels of IOA as high as possible (e.g., 90% or more) but consider the factors that might contribute to lower levels and make adjustments as warranted by these factors.
IOA can be calculated in a variety of ways. How it is computed depends on the dimension of the behav- ior being evaluated and how it is measured. Next we describe common methods for calculating IOA.
Frequency Recording To calculate IOA on frequency recording, the smaller frequency is divided by the larger frequency. For example, if one observer records 40 occurrences of a target behavior and a second independent observer records 35, the percentage of IOA during that observation session is 35/40, or 87.5%. The lim- itation of IOA in frequency recording is that there is no evidence that the two observers recorded the same behavioral event even when IOA is high. For example, if one observer recorded nine instances of the behavior and the other observer recorded 10 instances, the two observers ostensibly agreed on nine of the 10 instances for an IOA of 90%. It is pos- sible, however, that the observers were actually recording different instances of the behavior. One way to increase confidence that the two observers were agreeing on specific responses in frequency
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IOA is to collect frequency data in intervals and then compare the frequency in each interval (see Frequency Within Interval section later in this chapter). Dividing the observation period into shorter, equal intervals permits a closer look at the recording of frequencies in shorter time blocks. In this way, there can be more confidence that the observers recorded the same instances of the behav- ior when agreement is high. To further enhance confidence that observers are recording the same behavioral events, it is possible to collect data on behavior as it occurs in real time. With real-time recording, it is possible to determine whether there is exact agreement on each instance of the behavior.
Real-Time Recording When using real-time recording, the onset and offset of the behavior are recorded on a second-by-second basis. Therefore, IOA can be calculated by dividing the number of seconds in which the two observers agreed that the behavior was or was not occurring by the number of seconds in the observation ses- sion. Typically, an agreement on the onset and offset of the behavior can be defined as occurring when both observers recorded the onset or offset at exactly the same second. This form of IOA is the most strin- gent because agreement is calculated for every sec- ond of the observation period (e.g., Rapp, Miltenberger, & Long, 1998; Rapp, Miltenberger, Long, et al., 1998). Alternatively, IOA could be con- ducted on the frequency of the behavior, but an agreement would only be scored when both observ- ers recorded the onset of the behavior at the same instant or within a small window of time (e.g., within 1 or 2 seconds of each other).
Duration Recording IOA for duration recording is calculated by dividing the smaller duration by the larger duration. For example, if one observer records 90 minutes of break time taken in an 8-hour shift and the reliabil- ity observer records 85 minutes, the agreement between observers is 85/90, or 94.4%. The same lim- itation described earlier for IOA on frequency recording pertains to IOA on duration recording. Although the duration recorded by the two observ- ers may be similar, unless the data are time stamped,
there is no evidence that the two observers were recording the same instances of the behavior. Real- time recording is a way to overcome this problem.
Interval and Time-Sample Recording Computing IOA with interval data requires an interval- by-interval check for agreement on the occurrence and nonoccurrence of the behavior throughout the observation period. The number of intervals of agree- ment is then divided by the number of intervals in the observation period to produce a percentage of agree- ment. An agreement is defined as an interval in which both observers had a marked interval (indicating that the behavior occurred) or an unmarked interval (indi- cating that the behavior did not occur). Using only one target behavior for this example, consider a 10-minute observation session with data recorded at 10-second intervals (60 intervals total). If the number of intervals of observation with agreements is 56 of 60, the percentage of IOA is 56/60, or 93.3%.
Two variations of IOA calculations for interval recording, which correct for chance agreement with low-rate and high-rate behavior, are occurrence- only and nonoccurrence-only calculations. The occurrence-only calculation is used with low-rate behavior (from which chance agreement on nonoc- currence is high) and involves calculating IOA using only agreements on occurrence and removing agree- ments on nonoccurrence from consideration (agree- ments on occurrence divided by agreements plus disagreements on occurrence). The nonoccurrence- only calculation is used with high-rate behavior (from which chance agreement on occurrence is high) and involves calculation of IOA using only agreements on nonoccurrence and removing agree- ments on occurrence from consideration (agree- ments on nonoccurrence divided by agreements plus disagreements on nonoccurrence).
Cohen’s Kappa Kappa is another method of calculating observer agreement, but it corrects for the probability that two observers will agree as a result of chance alone. Kappa is computed using the following formula:
= − −
P P
P o c
c 1
,
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where Po is the proportion of agreement between observers (sum of agreements on occurrences and nonoccurrences divided by the total number of intervals) and Pc is the proportion of agreement expected by chance. The latter may be obtained using the following formula:
P I
c
o o n n= ( ) ( ) + ( ) ( ) OO11 OO22 OO11 OO22
2 ,
where O1o is the number of occurrences recorded by Observer 1, O2o is the number of occurrences recorded by Observer 2; O1n and O2n are nonoccur- rence counts, and I is the number of observations made by each observer.
For example if Observer 1 scored nine intervals out of 10 and Observer 2 scored eight intervals out of 10 (see Exhibit 6.1), kappa would be calculated as follows: Po = .90; PC = (72 + 2)/102 = .74, κ = .62.
Kappa values can range from −1 to 1, with 0 reflecting a chance level of agreement. No single rule for interpreting an obtained kappa value may be given because the number of different categories into which behavior may be classified will affect kappa. If only two categories are used (e.g., occur- rence vs. nonoccurrence), then the probability of a chance agreement is higher than if more categories had been used. Higher probabilities of chance agree- ment are reflected in lower kappa values. Thus, if the preceding example had used three categories (e.g., slow-, medium-, or high-rate responding) and IOA had been the same (90%), then kappa would have been more than .62.
Kappa can be affected by other factors, including the distribution of the ratings of the observers (Sim & Wright, 2005). Because these latter factors have little to do with the degree to which two observers agree, there is little agreement on what constitutes an acceptable kappa value. Within the social sci- ences, Kazdin (2010) suggested that a kappa value of 0.7 or higher reflects an acceptable level of agree- ment. Lower criteria for acceptable kappa values may be found (e.g., Fleiss, 1981; Landis & Koch, 1977), but these are as arbitrary as the cutoff sug- gested by Kazdin (von Eye & von Eye, 2008). Per- haps for this reason, kappa is less often used by applied behavior analysts than is IOA.
Frequency Within Interval Calculating IOA for frequency within interval mini- mizes the limitation identified for IOA on frequency recording (high agreement even though the two observers might be recording different instances of behavior). For example, if agreement is calculated within each of a series of 20-second intervals, then there is no chance that a response recorded by Observer A in Interval 1 will be counted as an agree- ment with a different response recorded by Observer B in Interval 12. To calculate frequency-within-in- terval agreement, calculate a percentage of agree- ment between observers for each interval (smaller number divided by larger number), sum the per- centages for all the intervals, and divide by the num- ber of intervals in the observation period. Exhibit 6.2 illustrates an IOA calculation for frequency-within- interval data for 10 intervals for two observers. Each X corresponds to an occurrence of the behavior in an interval.
Ethical Considerations Several ethical issues must be considered when con- ducting observations and measurement as part of research or clinical practice in applied behavior analysis (e.g., Bailey & Burch, 2005). First, a behav- ior analyst should observe and record the person’s behavior only after receiving written consent from the individual or the individual’s parent or guardian. As part of the consent process, the individual must be apprised of and agree to the ways in which the data will be used (research presentation or publication,
Exhibit 6.1 Recordings for Observer 1 and Observer 2 in 10
Observation Intervals
Interval
1 2 3 4 5 6 7 8 9 10 Observer 1
X X X X X X X X X Observer 2
X X X X X X X X
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clinical decision making). If the behavior analyst identifies new uses for the data after the original consent has been obtained, new consent must be obtained from the individual for the new ways in which the data will be used. Second, the individual must know when and where observation will take place unless the individual provides written consent for surreptitious or unannounced observation. Third, observation and recording must take place in such a way that confidentiality is maintained for the individual receiving services or participating in research. To maintain confidentiality, the observer must not draw attention to the person being observed and must not inform any other people about the observations unless the individual being observed has provided written permission to do so. In addition, behavior analysts must use pseudonyms and disguise other identifying information in pre- sentations and publications. Fourth, observers must treat the individual being observed and others in the setting with dignity and respect at all times during the course of their participation in research or as they are receiving clinical services.
SUMMARy
Observation and measurement are at the heart of applied behavior analysis because behavior (and its controlling variables) is the subject matter of both research and practice. As discussed in this chapter,
adequate measurement of behavior requires clear definitions of the target behavior, precise specifica- tions of recording logistics and procedures, appro- priate choice of recording devices, and consideration of reactivity and IOA. The validity of conclusions that can be drawn from experimental manipulations of controlling variables or evaluations of treatment effectiveness depends on the adequacy of the obser- vation and measurement of the behaviors targeted in these endeavors.
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Exhibit 6.2 Frequency-Within-Interval Recordings for Two Observers
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Interval
1 2 3 4 5 6 7 8 9 10 Observer 1
XXX X XX XX X XXX XX 67% 100% 100% 100% 100% 100% 50% 100% 50% 100%
Observer 2
XX X XX XX XX XXX X
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