Self-study
Support To test the claim that vitamin C is effective in treating acne, scientists administered it to one group of subjects and a placebo to a control group. ███ █████ █████████ ███████ █ ███ ████ ██████ ████ ██████ ███ █████ ████ ███ ███ ███████ ██████ ██ ███ ████████████ ███████████ ████████ ████ ████ ██ ███ ████████ ██ ████ █████ ████ █████ ████ ██ ████ ████ ████ ██████ █████ █████ ███ █████ ███ █████ ██ ██████████ ██ ███ ████████ ██ ████ ███ █████ ███████ ███ ███ ███████ ██████████ ██ ███ ███████████ ████████ ████ ███████ █ ███ ██ ████ ███████ ██ ████████ ███ ████████ ██ █████
Summarize Argument: Phenomenon-Hypothesis
The author hypothesizes that vitamin C does not help reduce the severity of acne. This is based on a study showing no difference in the severity of acne between a group given vitamin C and a control group given a placebo.
Notable Assumptions
The argument assumes that there were no differences between the vitamin C group and the control group that could have made the vitamin C group’s acne more severe, thus masking the beneficial effect of vitamin C. The argument also assumes that before the study began, the vitamin C group did not start with more severe acne than the control group, which is another way beneficial effects of vitamin C could have been masked.
25.
Which one of the following, ██ █████ ████ █████████ ███████ ███ █████████
a
The subjects who ████ █████ ███████ █ ███ █ ███████ ██ █████████ ████ ████ ██████ ████ ████ ███ ███ ████████ █████████ █ ████████
This explains how the two groups might end up with the same severity of acne even if vitamin C does help to reduce severity. Vitamin C may have reduced the severity down to the same level as that of the placebo group.
Alternate explanation
Alternate explanation
Weaken: Introduce or support an alternate explanation for a phenomenon.
Strengthen: Helps to eliminate an alternate explanation for a phenomenon.
b
None of the ████████ ███ ████ █████ ███████ █ ████ ██████████ █████ ██ ███████ █ ██ █████ ████
If this has any impact at all, this might strengthen the argument by showing that the vitamin C group didn’t take more vitamin C than they were supposed to. Learning that study subjects didn’t do things they weren’t supposed to doesn’t undermine an argument based on a study.
Directionally wrong
Directionally wrong
Answers that, if they have any effect, do the opposite of what we want (weaken when we're trying to strengthen, or strengthen when we're trying to weaken).
c
During the study, ███ ████████ ██ ███ █████████ ████ ███ █████ ████ ███ ████████ ████████
How the subjects’ acne compared to the national average is irrelevant because we’re comparing the severity of the vitamin C group’s acne to the severity of the placebo group’s.
d
Some of the ████████ ███ ████ █████ ████████ ████████ █████ ██████ ███ █████ ████ ███ █████████ ████ ██ ███████ ██
We have no reason to think this isn’t equally true of the vitamin C group. In addition, “some” subjects could just be a single person, which would not necessarily affect the overall average results observed in the placebo group.
Illusory inconsistency
Illusory inconsistency
Answer is attractive because it seems to (but doesn't actually) contradict the premises or conclusion. In other words, it feints an attack on the premises or conclusion. If correlation is present, the answer choice is often merely an outlier datapoint, which is actually entirely consistent with the correlation.
e
Some of the ████████ ███ ████ █████ █████ ████ ████████ ███ ███ ████████ ████ ███ █████ ████ ████ ██████
The conclusion isn’t based on data about the people that knew they got the placebo or the vitamin C. It’s based on data about the people that didn’t know whether they got the placebo or the vitamin C.
Illusory inconsistency
Illusory inconsistency
Answer is attractive because it seems to (but doesn't actually) contradict the premises or conclusion. In other words, it feints an attack on the premises or conclusion. If correlation is present, the answer choice is often merely an outlier datapoint, which is actually entirely consistent with the correlation.