PrepTest 133, Section 3, Question 6
A transit company's bus drivers are evaluated by(39 more words not shown)
Which one of the following(8 more words not shown)
- AThere is no(14 more words not shown)
- BThe supervisors are(7 more words not shown)
- CFor most bus(16 more words not shown)
- DThe bus drivers(19 more words not shown)
- EThe bus drivers(11 more words not shown)
Reading the argument
I'd drive carefully if my supervisor were sitting behind me. But another driver might get so nervous about being watched that they start making mistakes.
That's the problem with saying the supervisor affects everyone. The author treats that as a reason we can still trust the ranking: the best drivers under observation will probably also be the best drivers on a normal day. But affecting everyone isn't the same as affecting everyone equally.
Imagine one driver whose confidence falls apart under observation and another who finds the ride-along only mildly annoying. The first driver's unusually bad performance could put them below the second driver, even if they normally drive better. Or a driver who is careless alone might put on exceptionally good behavior during the evaluation. Different responses could scramble the ranking.
What we’re looking for
The assumption question asks what the author needs to take for granted to dismiss this problem. The effect must be roughly comparable across drivers. Otherwise, doing best with the supervisor aboard could tell us more about handling supervision than about normal driving.
Working the answers
- A
There could be another effective method, such as an unobtrusive evaluation, and this argument could still claim that the ride-along ranking works. The author needs a reason to trust this method, not a reason to rule out every alternative.
- B
The supervisors needn't be excellent judges for the particular comparison the argument makes. Even an accurately observed supervised performance might differ from normal performance. B praises the evaluators without addressing whether supervision changes some drivers much more than others.
- C
Why slightly worse? The passage says performance is affected, not that the effect always goes in that direction or has that size. Some drivers might improve when watched. The argument needs a comparable effect across drivers; it doesn't need the particular claim that most get slightly worse.
- DCorrect
Roughly the same effect, in the same direction and to the same extent, gives the author a basis for expecting the ranking to survive. If supervision changes everyone's performance similarly, the drivers who stand out during the evaluation are more plausibly the ones who stand out normally. If it helps one driver and badly rattles another, the author's reassurance breaks down.
- E
Nobody is asking the drivers to score their own driving. Their ability to assess themselves doesn't resolve whether a supervisor's presence changes the performances being compared. The argument could work even if the drivers were poor judges of their own abilities.
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