PrepTest 136

Correct. Argument or Facts:
Argument

Valid or Flawed:
Flawed

Question Type:
Strengthen

Stimulus Summary:
M: We started offering free shipping and then saw an increase in sales, so the free shipping caused the increase.

Answer Anticipation:
Two changes that are correlated? A conclusion about one causing the other? This stimulus doesn't even use a word that implies causality—it uses "caused" itself. This is a correlation/causation flaw, and so we can strengthen it using the normal methods:
(1) Eliminate an alternative cause of the sales increase (e.g., other policy changes rolled out with the free shipping)
(2) More examples of cause and effect going together (e.g., a competitor that did the same thing and saw the same results)
(3) A "control" (e.g., the company had one division that still charges shipping and it didn't see an increase in sales)
(4) An explanation of how the causality worked (probably won't show up here since that's pretty obvious)

Answer Explanation:
This is an example of a "control"—showing that where the cause isn't, neither is the effect. As such, it strengthens the causal relationship in the stimulus.

Key Takeaway:
If you get a correlation/causation flaw-based Strengthen question, run into the answers with the common ones in mind! It should be a question you can get right a little faster than the average.

Incorrect. If anything, this would suggest an alternative cause since consumers might be largely unaware of the change in policy.

Incorrect. There's no discussion of profits, so this answer is out of scope.

Incorrect. Without knowing what happened to the sales at these other companies, we can't analyze the impact this has on the argument.

Incorrect. This answer could affect the argument if it discussed sales at those companies, but it doesn't, so it's neutral.