PrepTest 138, Section 3, Question 3
Statistics reveal that more collisions between bicycles and(32 more words not shown)
The argument is most vulnerable(7 more words not shown)
- Aoverlooks the possibility(29 more words not shown)
- Bfails to address(22 more words not shown)
- Ctakes for granted(16 more words not shown)
- Dconcludes that adding(26 more words not shown)
- Etakes statistical evidence(18 more words not shown)
Reading the argument
What if there are simply more cyclists on roads with bike lanes? More cyclists means more opportunities for a bicycle and a car to collide. We could therefore see more total collisions on those roads even if each individual cyclist faced a lower risk. Counting crashes without considering how many people are riding doesn't tell us which roads are safer for a cyclist.
What we’re looking for
The author uses those totals to oppose adding bike lanes. For the flaw question, ask what makes that comparison unreliable: are we comparing similar amounts of cycling, or much heavier use on one set of roads? Until we consider that possibility, the larger collision count doesn't settle whether the lanes improve safety.
Working the answers
- A
Equal injury severity wouldn't expose the problem with the author's reasoning. If collisions were just as serious on both kinds of road, we'd still need to know how common they were relative to the amount of cycling. A doesn't supply the overlooked reason why more total crashes could coexist with safer riding.
- BCorrect
This is the possibility we wanted the author to consider. Roads with bike lanes may attract more bicyclists, giving us more opportunities for collisions. The larger total could reflect heavier use instead of greater danger to an individual rider. We don't have to prove that the lanes are safer; showing why these totals fail to settle the comparison identifies the flaw.
- C
The argument doesn't assume that protecting cyclists also protects motorists. It questions whether adding lanes will protect cyclists at all. No conclusion about drivers' safety is part of the reasoning.
- D
The premise isn't that only some roads with lanes are safe. It's that more bicycle–vehicle collisions occur on roads with lanes than on roads without them. D describes a different starting point, so it can't accurately describe the inference made here.
- E
This would fit an argument that said, in effect, 'The evidence doesn't show that lanes improve safety, so it proves that lanes do not improve safety.' Our author instead treats a particular statistic—the higher collision total—as evidence against the benefit of lanes. The defect is in that comparison: it leaves out how much cycling occurs. B identifies the missing information directly.
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