self-report measure - A method of measuring a variable in which people answer questions about
themselves in a questionnaire or interview.
observational measure - A method of measuring a variable by recording observable behaviors or
physical traces of behaviors. Also called behavioral measure.
physiological measure - A method of measuring a variable by recording biological data.
categorical variables - A variable whose levels are categories (e.g., male and female). Also called nominal
variable.
quantitative variables - A variable whose values can be recorded as meaningful numbers.
ordinal scale - A quantitative measurement scale whose levels represent a ranked order, and in which
distances between levels are not equal (e.g., order of finishers in a race). See also: interval scale, ratio
scale.
interval scale - A quantitative measurement scale that has no “true zero,” and in which the numerals
represent equal intervals (distances) between levels (e.g., temperature in degrees). See also: ordinal
scale, ratio scale.
ratio scale - A quantitative measurement scale in which the numerals have equal intervals and the value
of zero truly means “none” of the variable being measured. See also: interval scale, ordinal scale.
Reliability - The consistency of the results of a measure.
validity - The appropriateness of a conclusion or decision. See also: construct validity, external validity,
internal validity, statistical validity.
test-retest reliability - The consistency in results every time a measure is used.
interrater reliability - The degree to which two or more coders or observers give consistent ratings of a
set of targets.
internal reliability - In a measure that contains several items, the consistency in a pattern of answers, no
matter how a question is phrased. Also called internal consistency.
correlation coefficient - A single number, ranging from –1.0 to 1.0, that indicates the strength and
direction of an association between two variables.
slope direction - The upward, downward, or neutral slope of the cluster of data points in a scatterplot.
strength - A description of an association indicating how closely the data points in a scatterplot cluster
along a line of best fit drawn through them.
Strong positive will be close to 1
Cronbach’s alpha - A correlation-based statistic that measures a scale’s internal reliability. Also called
coefficient alpha.
face validity - The extent to which a measure is subjectively considered a plausible operationalization of
the conceptual variable in question.
content validity - The extent to which a measure captures all parts of a defined construct.
Criterion validity - An empirical form of measurement validity that establishes the extent to which a
measure is associated with a behavioral outcome with which it should be associated.
known-groups paradigm - A method for establishing criterion validity, in which a researcher tests two or
more groups who are known to differ on the variable of interest, to ensure that they score differently on
a measure of that variable.
convergent validity - An empirical test of the extent to which a self-report measure correlates with other
measures of a theoretically similar construct. See also: discriminant validity.
