A retrospective study is a scientific study that tries to determine the causes of subjects' present characteristics b...

Katherine on January 23, 2019

Hi @alymathieu,

I’m happy to help. The question asks you to choose the answer that, if assumed, enables the argument to be properly drawn. In order to answer this question correctly, let’s examine the argument closely and see whether we can identify any premises that are missing (and therefore must be assumed to be true) in order for the conclusion to be properly drawn.

The argument begins by describing a kind of scientific study called a “retrospective study.” These studies determine the causes of present behavior by studying the connection between present characteristics and past circumstances. The argument concludes that this kind of study cannot reliably determine causes of human behavior because it relies on human subjects to self-report about their pasts. Why does this fact prevent the study from being reliable? The argument does not say so explicitly, but it assumes that people are not entirely accurate when self-reporting about their past. Because scientists "must" rely on these self-reports in studies of human subjects, it effects the reliability of the study. Answer C correctly identifies this necessary assumption by saying the human “subjects’ reports about their own pasts are highly susceptible to inaccuracy.”

Answer A is incorrect. The argument says that this kind of study CANNOT reliably determine causes of human present behavior because it MUST use the subjects’ own reports of their pasts. Answer A suggests that there may be a way to conduct this study on human subjects without relying on inaccurate reports of the subjects’ pasts. The argument does not suggest this is possible, therefore this is incorrect.

Answer B says that this kind of study cannot determine causes of human behavior unless there are correlations between present behavior and what happened in the past. This answer restates the description of this kind of study explained in the first sentence. The reliability of using this kind of study to determine causes of human behavior is not a matter of whether there are correlations and instead the accuracy of human subjects’ accounts of their own pasts.

Answer D says that if a study uses only accurate reports of the subject’s past, then it can determine causes of present behavior. This answer is not a missing assumption of the argument. Instead, it draws another conclusion that is the inverse of the argument's conclusion. While the argument says that the inaccuracy of human subjects’ accounts of their past is the reason this kind of study does not work on human subjects, it does not state the reverse - if the study used accurate reports, it could determine causes of subject’s present characteristics.

Answer E says that EVERY scientific study of this kind must use the subjects’ reports about their own pasts. While the argument says that studies involving human subjects must rely on the subjects’ own reports about their pasts, it does not suggest that this is the case for EVERY scientific study. Instead, this limitation seems unique to studies involving human subjects and poses difficulties for application of this study to this type of subject in a way it would not for others.

I hope this is helpful. Please reach out with other questions.