Logical reasoning PrepTest 144 · Section 4 · Question 7

Incorrect. The main conclusion—that fish can lower cholesterol levels—is strengthened by the fact that the two groups started with the same levels but the one that ate fish saw them decrease.

Incorrect. Studies—and the details of how they were run—will almost never serve as the main point of an argument. They're support, allowing the author of an argument to back up a conclusion with the results.

Correct. Argument or Facts:
Argument

Valid or Flawed:
Flawed

Question Type:
Argument Structure

Stimulus Summary:
Study:
Group 1 + 2 Ð Similar cholesterol levels before study
Group 1 Ð Diet with fish
Group 2 Ð Similar diet without fish
End of study Ð Group 1 had lower cholesterol levels

Answer Anticipation:
This stimulus goes into pretty fine detail about the study that was done, which is nice! We get a split between two groups that started out with a similarity (cholesterol levels), but then a difference was established in their diet and one group ended up with lower cholesterol levels. Normally, we'd start going into correlation/causation, but this is an Argument Structure question, so the logic is only relevant in how it defines the role of statements—not in whether it's valid or flawed! So we only need to note that there is a correlation/causation jump here.

The statement in question sets the baseline before the study—both groups started with the same/similar cholesterol levels. This is important because otherwise the study would have a flaw—the first group may have started with lower levels. Studies should generally establish a baseline (and also a control group).

In any case, the correct answer should say that the statement in question establishes a baseline for the groups so that any changes can be measured against it.

Answer Explanation:
While not exactly what we anticipated, setting a baseline does rule out an alternative explanation—that the groups started with different cholesterol levels, and Group 1 didn't lower their levels at all but rather started lower.

Key Takeaway:
This argument featured a correlation/causation flaw, and those generally have correct answers that talk about alternative explanations. Even though this is an Argument Structure question, that still panned out, as the statement in question—in setting a baseline for the study—itself ruled out an alternative explanation. These concepts aren't siloed within individual question types—what you know about logic from studying one type of question can help you find correct answers in others.

Incorrect. The purpose of the study was to analyze cholesterol level and diet—that's laid out in the second sentence, not the statement in question.

Incorrect. An alternative explanation would need to account for differing levels of cholesterol in the two groups, and the statement in question says that they had the same levels.