LR Question 21 Explanation
QUESTION TEXT: Safety consultant: Judged by the number of injuries…
QUESTION TYPE: Strengthen
CONCLUSION: Minivans are probably safer because they tend to be driven by safe drivers.
REASONING: Crash tests show that minivans aren’t safer in crashes than similarly sized vehicles are. This is true even though minivans have the lowest number of injuries per licensed vehicle.
ANALYSIS: This argument makes a bunch of errors:
- The consultant forget to test minivans against smaller vehicles. Maybe minivans are safer because they are bigger.
- The consultant ignored whether minivans are less likely to get into a crash in the first place.
We can strengthen the argument by accounting for either of these. So the right answer will probably say something like one of either:
- Crash tests show that minivans aren’t safer than small vehicles, either.
- Minivans are not less likely to get into accidents.
___________
- This weakens the argument. Minivans don’t perform better in crash tests. So this shows that safe drivers aren’t more likely to pick minivans.
- This weakens the argument by showing that minivans are equally likely to get in accidents. Potentially, that means their drivers aren’t especially good!
The stimulus says minivans aren’t better at protecting people. This answer says that minivans have the same number of accidents.
The only remaining possibility is therefore that minivans have fewer passengers to get injured. That is not what the author was concluding. -
This adds confusion. Normally, more passengers in a vehicle would mean more injuries in an accident. But, we know two things:
1. Minivans have a low number of injuries per accident.
2. Minivans don’t protect these people (compared to similarly sized vehicles)So, something else must be causing minivans to have a low injury rate per vehicle, despite the high number of people in vehicles.
The trouble is, we don’t know which alternate cause this supports. Are minivans safer because:
- Drivers are safer, or
- Because minivans are safe to drive, and thus unlikely to get into an accident in the first place.
This answer supports any alternate possibility. It doesn’t strengthen the stimulus specifically.
- This weakens the argument by introducing an alternate hypothesis. Maybe minivans have a good safety record because they are large.
(The stimulus did say that minivans aren’t better than other large vehicles. But, this answer suggests that minivans are safer than small vehicles due to size, rather than driver quality!) - CORRECT. This might seem like a weird strengthen answer. How does worse braking make minivan drivers better?
Well, we know minivans don’t protect occupants. And this answer says minivans are hard to drive. And yet, minivans have excellent safety records.
So how could this be so? Well, maybe minivan drivers are excellent. Effectively, this answer strengthens the argument by removing a competing possibility. (If minivans had better handling than other vehicles, then they would be safer to drive even if drivers were not especially skilled.)
More Resources for Strengthen Questions
- Intro Course lesson: This intro course lesson covers Strengthen questions.
- Mastery Seminar lesson: This LR Mastery seminar lesson covers strengthen questions.
I’m not sure the first error you attribute to the consultant (the failure to compare the minivan to smaller vehicles) is an error. His conclusion, that the low number of injuries is due to minivans being driven by safer drivers, is supported by the study regardless. By showing that at least some other cars are as safe in accidents as minivans, you have ruled out one possible explanation for the injury per licensed vehicle statistic.
Consider this experiment: people in Guardco bulletproof vests survive bullet wounds better than people wearing other clothing. But, in controlled experiments people wearing guardco vests survive no better than people wearing defenseco bulletproof vests.
So, guardco vests are no safer than other clothing such as sweaters. Probably people who wear guardco vests are hardier people who can resist gunshots more easily.
Here, I’m comparing people in bulletproof vests to other bulletproof vests, and then claiming that bulletproof vests aren’t safer than regular clothing.
This is clearly dumb, because bulletproof vests stop bullets and regular shirts don’t.
Bulletproof vest from guardco = minivan
Bulletproof vest from defenseco = similarly sized vehicle
Regular shirt = smaller vehicle
This is why I said the author should have compared minivans to smaller vehicles. It’s possible that all large vehicles are safer than small vehicles. If you compared small vehicles to minivans you might find the minivans are safer, just as bulletproof vests are safer than normal shirts.
Note: This is an old comment but I wanted to clarify the point.