LSAT 132 | Section 2 | Logical Reasoning: Q9

LR Question 9 Explanation

QUESTION TEXT: A retrospective study is a scientific study that tries…

QUESTION TYPE: Sufficient Assumption

CONCLUSION: Retrospective studies aren’t reliable ways to learn about humans’ present characteristics.

REASONING: Retrospective studies depend on human subjects’ own reports.

ANALYSIS: You must prove the conclusion is true. You only have one piece of evidence. You can prove the conclusion by adding a premise that says “if the evidence is true, the conclusion is true”. So you’re looking for something that says any study based on subjective reports is useless.

Here’s a diagram of the evidence and the conclusion:

Subjective Unreliable

There’s no link between them. So here’s the new premise we need:

Subjective ➞ Unreliable

The answers are really dense. You need to focus, and keep in mind what you’re looking for. Skip answers that aren’t talking about the right thing, and be ruthless in your search for the right sufficient condition.

___________

1. What a wishy-washy answer. This can’t prove anything. I think it’s safe to say that “may depend at least in part” has never been a sufficient condition on the LSAT. We’re looking for something definite that proves the conclusion.
2. This says “if there are no correlations, the study can’t work”. This answer is a total red herring. Correlations were never mentioned.
3. CORRECT. Retrospective studies depend on subjective reports. If the subjective reports are unreliable, then the studies will be unreliable.
4. This answer adds a sufficient condition for a study being reliable. We need a sufficient condition for a study not being reliable.
5. This just tells us that studies must use subjective reports. This doesn’t tell us the studies are unreliable.

Recap: The question begins with “A retrospective study is a scientific study”. It is a Sufficient Assumption question. To practice more Sufficient Assumption questions, have a look at the LSAT Questions by Type page.