MCAT® ExamCritical Analysis and Reasoning SkillsEasy
A research team is studying the impact of a new educational program on student performance. They observe that students who voluntarily enroll in the program show significantly higher test scores than those who do not. However, the researchers are concerned that this observed difference might not solely be due to the program's effectiveness, but rather to an inherent motivation difference between the two groups. This concern best reflects an awareness of which common research challenge?
- ASelection Bias
- BExperimenter Bias
- CSocial Desirability Bias
- DObserver-Expectancy Effect
Show answer & explanationAnswer & explanation
Correct answer: A. Selection Bias
The researchers are noticing that the groups being compared (those who voluntarily enroll vs. those who don't) are not inherently similar, leading to a skewed comparison. This difference in group characteristics due to the way participants are chosen or choose to participate is known as selection bias.
Why the other options are wrong
- B. Experimenter bias refers to researchers' expectations influencing the results, not the participants' inherent differences.
- C. Social desirability bias involves participants altering their responses to appear more favorable, which is not the primary concern here.
- D. Observer-expectancy effect is a form of experimenter bias where observers' expectations influence their perceptions, not the participants' self-selection.
Selection Bias
Selection bias occurs when the method of selecting participants for a study results in a sample that is not representative of the population being studied, or when the comparison groups in a study are not truly equivalent.
- Occurs during participant selection or assignment.
- Leads to non-equivalent groups.
- Threatens the internal validity of a study.
Memory trick: Careful Who You Pick, Or Your Study's Flawed Quick.