Discussion Board: Confounding Variables
Internal validity in a research study is the extent to which changes in the dependent variable can confidently be attributed to the influence of the independent variable rather than to possible confounding variables. In other words, was it really the independent variable that had an effect on the dependent variable or did something else cause the effect?
For example, presume that an instructor wants to try a new reading efficiency strategy to improve reading comprehension of college students in an online course. The instructor divides the class into two equal groups. One group (the experimental group) reads a passage using the new reading strategy taught by the instructor. The other group (the control group) reads the same passage but is not exposed to the new strategy. Next, both groups of students complete a reading comprehension test. The assumption is that if the group exposed to the new reading strategy scored higher than the other group, the new reading strategy is effective.
What else could explain the difference in scores? Is it possible that the students enrolled in the group that learned the new strategy already had high reading comprehension skills? What if this group already knew more about the information in the reading passage? Could the instructor have inadvertently biased the study because he taught the new reading strategy, and he selected the reading passages that both groups read?
Possible situations, or reasons, that could interfere with obtaining accurate results are called confounds, and could be a threat to the internal validity of a study. It is important to keep in mind though, that the presence of a possible confounding variable in a study does not necessarily mean it is responsible for obtained results. Rather, the independent variable (e.g., the reading intervention) may have actually had an effect on the dependent variable (the test results).
In this Discussion, you will examine possible confounding variable(s) in research studies from your course textbook and apply methodology for addressing and/or eliminating the possible confound(s).
• Indicate the letter of the scenario you selected in the "Subject" field of your post. You should be addressing a scenario different from those posted, unless your colleagues have already addressed all nine scenarios. Identify and explain the possible confounding variable(s) (e.g., demand characteristics, placebo effect) in your chosen scenario.
• Drawing from the Learning Resources, explain a specific research design (e.g., 2x2 factorial design, repeated measures design) the researcher(s) could use to control for confounding variables.
The response must include a reference list. Using one-inch margins, double-space, Times New Roman 12 pnt font and APA style of writing and citations.