PrepTest 158, Section 2, Question 18
Records reveal that of physical therapy patients who(81 more words not shown)
The reasoning in the argument(11 more words not shown)
- Apresumes, without providing(26 more words not shown)
- Bprovides no information(13 more words not shown)
- Coverlooks the possibility(22 more words not shown)
- Dfails to indicate(20 more words not shown)
- Eoverlooks the possibility(16 more words not shown)
Reading the argument
The short treatments produced the same reported rate of major improvement for both kinds of practitioner. My first question would be whether a specialist's advantage shows up over a longer period. But the passage addresses that too: among the longer treatments, the rate is again the same for both groups.
How much longer were those treatments? Seven weeks? Several months? The category “longer than six weeks” can include a year, but the description doesn't tell us how many patients actually received treatment over different longer periods. I wouldn't want to assume these figures settle every possible treatment duration.
What we’re looking for
More broadly, the author moves from equal rates in these records to a claim about your choice of practitioner: it won't affect your chances of major improvement. That's a strong use of these group results. For the flaw question, look for a reason the comparison might not tell us which practitioner would help a particular patient. The duration question is one concern to keep in mind; an answer could expose another.
Working the answers
- A
Both the evidence and the conclusion concern major improvement. The argument doesn't start with equal rates of any improvement and then assume equal rates of major improvement. A describes a change in the outcome being measured that never occurs here.
- B
This asks which injuries need shorter or longer treatment. It doesn't explain why, for a patient's injury, choosing a specialist instead of a general practitioner could change the chance of improvement. Missing descriptive detail isn't automatically the reason this comparison fails.
- C
The evidence comes from records of improvement. We aren't told that these figures are patients' favorable ratings of their practitioners. C offers a possible reporting bias without connecting it to how the improvement figures were obtained. We shouldn't invent that connection.
- D
The groups don't need exactly the same number of patients for their percentages to be compared. A rate of 50 percent can describe 50 out of 100 or 100 out of 200. Those different totals don't, by themselves, make the rates misleading. D doesn't identify why the same overall rate might hide an important difference for a particular injury.
- ECorrect
The two kinds of practitioner could be better at treating different injuries. Equal overall rates wouldn't show that they are interchangeable for the injury you have.
Imagine the general practitioners mainly treating sprained ankles while the specialists mainly treat serious knee injuries. A 50 percent improvement rate in each group wouldn't mean the practitioners were equally effective at treating the same condition. They haven't been tested on the same mix of cases. A specialist might be the better choice for the knee injury even though the overall percentages match.
We aren't told that this is the actual patient mix. The example shows what the argument leaves open: performance across different types of injury can be hidden inside equal overall figures. That blocks the leap to saying your choice of practitioner won't matter.
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