Final Paper: Research Proposal
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PSY326ResearchMethodsWeek5Guidance.docxPSY326 Research Methods Week 5 Guidance
Welcome to the final week! View the video on the Week 5 overview screen for an introduction to the topics and assignments. Read Chapter 5 of your textbook. An article by Dr. Anthony Onwuegbuzie about threats to validity is recommended reading (see the course guide). To get the article, go to the Ashford Library, find the ERIC database and search for “Onwuegbuzie” as the author and “internal and external validity” as either the title or subject.
After completing this instructional unit, you will:
· Evaluate the key components of the experimental design.
· Examine threats to both internal and external validity in experimental research.
In this week’s discussion, you will describe different ways that experimental and quasi-experimental studies can be designed, explain the differences between them, and discuss the ways that an independent variable can be manipulated in an experiment. Be sure to include an example of either an experiment or a quasi-experiment, and explain why the chosen design is appropriate for the situation in the example.
Remember that all discussions should cite at least two scholarly sources, so be sure to search the Ashford Library resources (including the Research Methods research guide) for journal articles that extend the information given in the textbook on experimental research. All references should be cited in APA format. See the Ashford Writing Center, under Learning Resources in the left navigation panel, for examples of correct APA style.
This week’s quiz will cover the concepts related to experimental and quasi-experimental research designs discussed in Chapter 5 of the textbook. The quiz is due on Sunday.
In the final paper due this week, you will prepare a research proposal for a new study on the topic of the study you critiqued in Week 3. What would you do to confirm or extend the research done in that study? Would you try a different research design or use the same one? Carefully review the final paper instructions and the feedback from your Week 3 assignment to help you prepare the final paper. Use the section headings from the assignment instructions to organize the paper and ensure that you have included all of the required information. Note that the section headings for the final paper are slightly different from the headings for the critique assignment.
The experiment has historically been considered the “gold standard” of research methods, if the purpose of the study is to establish causation. This is because the elements of control imposed in a well-conducted experiment make it possible to determine that the independent variable (the hypothesized cause) is the only factor that is influencing the dependent variable (the observed effect). Correlational designs can establish a relationship between variables, but they cannot prove a cause and effect relationship. Experimental research has traditionally been associated with quantitative research methods because in order to compare results and say that something is better or higher than something else, numbers have to be used in the comparison.
Experiments use all of the qualities of the scientific method: objectivity, precise measurements, control of other possible influencing factors, careful logical reasoning, and replication, as described in your textbook (Newman, 2016). To be considered a true experiment, a research study must have all three of these characteristics: (1) manipulation of an independent variable; (2) random assignment of participants to groups or conditions; and (3) control of extraneous variables. A quasi-experiment is a study that has some, but not all, of these characteristics. Variables which are presumed causes but cannot be manipulated by the researcher are sometimes called “quasi-independent” variables. If quasi-independent variables such as gender or race are of interest in a study, they must be used in conjunction with an independent variable that can be manipulated, such as an aspect of the environment, in order for the study to count as a true experiment. Without a manipulated independent variable, the study would be a quasi-experiment. Think about situations when it is either impossible or unethical to randomly assign people to conditions or to manipulate a variable. In these situations, a quasi-experimental design may be called for.
Random assignment means that after you have recruited a sample of participants, you use a random process to divide them into two groups, usually based on the values of the independent variable. Randomly assigning participants to groups guards against possible bias and helps assure that the groups will be equal on unknown or extraneous factors. The two groups are called treatment (or experimental) and control.
The treatment group receives some amount of the treatment and the control group receives either no treatment or a standard treatment – this is also called manipulation of the independent variable. Everything about the two groups should be the same except for their condition on the independent variable. After the treatment period is over, the researcher measures the dependent variable for all participants and compares the scores for the two groups. If the treatment group has a significantly different score than the control group, you can be fairly certain that the treatment was what made the difference.
For example, suppose you want to find out if a new method of teaching science is really better than the way it is currently being done. You would get a random sample of appropriate students and randomly assign them to groups. (If you can randomly assign students to groups, this would be an experiment, but if you have to use existing classes as the groups, it would be considered a quasi-experiment.) You have to watch out for possible problems, called threats to validity, such as students from different groups talking to each other about how they are being taught (this is called diffusion of treatment). Random assignment prevents bias (i.e., assigning your favorite students to a particular group) and it also helps you make sure that you don’t have all of the students who were already better at science in the same group. The groups should be as equal as possible at the beginning of the study.
In this example, the independent variable is the teaching method, which is assigned by the researcher. The dependent variable would be the score on a science test that all of the participants would take at the end of the study. If all goes well and the groups are really random and have an equal average on unknown factors that might affect knowledge or ability in the subject, you will be able to rely on the results of the comparison of test scores. So, if the treatment group’s average score is much higher than the control group’s average score, you can be reasonably confident that the new teaching method works better than the old method. If the average scores for the two groups are about the same, then you can conclude that both methods work just as well. Of course, if the control group has a higher average score than the treatment group, you won’t want to switch to the new teaching method!
There are two aspects of experimental validity – internal and external. Internal validity has to do with being able to be sure that the independent variable in your experiment was really the cause of any observed change in the dependent variable. Without internal validity, you may as well not bother doing the experiment, because the results cannot be trusted.
External validity, on the other hand, is desirable, but not essential in the same way that internal validity is. External validity concerns whether the results of the research can be generalized to people (or animals) other than the participants in the research sample.
Both aspects of validity need to be protected from threats, a few of which are described in Chapter 5 of the textbook. The Onwuegbuzie (2000) article contains a much more complete and detailed description of threats to internal and external validity. Controlling extraneous variables (things that might influence the dependent variable but are not part of the experiment) will help resolve many internal validity threats, but the more controls that are instituted to increase internal validity the less likely it is that external validity will be strong. Researchers must find a balance between internal and external validity.
If you have any questions about this week’s readings or assignments, email your instructor or post your question on the “Ask Your Instructor” forum. Remember, use the forum only for questions that may concern the whole class. For personal issues, use email.
References
Onwuegbuzie, A. J. (2000). Expanding the framework of internal and external validity in quantitative research. Retrieved from http://eric.ed.gov/
