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#19 - The use of automobile safety seats by children aged 4

smile22
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I am having a really hard time understanding how to strengthen this stimulus. In my evaluation of the stimulus, I found that the conclusion was that the increase in the use of automobile safety seats prevented child fatalities that otherwise would have occurred. So, this is essentially a causal claim, where the safety seats CAUSED :arrow: prevention of child fatalities

I think that this is a numbers type of question. How do I strengthen this?
KelseyWoods
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Hi smile22!

You are correct that we have a causal conclusion and that the conclusion is that the increase in the use of safety seats has prevented child fatalities. You're also correct that this is a Numbers and Percentages problem!

Let's breakdown the argument. Why does the author conclude that the increase in the use of safety seats is preventing child fatalities? He gives us a couple of statistics: the number of automobile accidents has increased 20 percent in the past 8 years but the number of young children killed in accidents has only risen 10 percent over that same period. Basically, he's telling us that, yes, the number of young children killed in accidents has gone up, but the number of serious accidents has gone up by an even larger percentage. So, more children would have died in those accidents if the safety seats hadn't protected them.

The problem is that the statistics he's given us don't fully support his conclusion. To determine whether the safety seats are preventing child fatalities, we need to compare the number of young children dying in accidents to the number of all accidents involving young children--not just the number of all accidents.

Think about it like this: Let's say the number of serious accidents increased by 20 percent, but most of those accidents involved only adults and older children. In fact, wouldn't it be possible for the overall number of accidents to go up but the number of accidents involving young children to go down? And if the number of accidents involving young children went down during the past 8 years but the number of young children killed in accidents went up, that would seriously call into question our author's conclusion that the safety seats are saving lives.

To strengthen this causal conclusion, we need to support the data. We need to show that the number of accidents involving young children went up by a larger percentage than the number of young children killed in accidents.

Answer choice (B) does this for us. Answer choice (B) states that the proportion of all serious accidents involving children has remained the same. That tells us that the number of serious accidents involving children has increased by 20 percent, just like the number of total serious accidents. This shows that the number of young children killed in accidents rose by less than the number of young children involved in accidents, and, therefore, the proportion of young children dying in accidents in which they are involved is lower than it was 8 years ago. Which, in turn, supports the conclusion that the safety seats are preventing fatalities.

We can make up some numbers to try to make it a little more clear. Let's say that this is what we had 8 years ago:

Total # serious accidents: 100
Proportion of accidents involving young children: 40%
# serious accidents involving children: 40 (40% of 100)
# of young children killed: 10
Proportion of children killed in serious accidents: 25% (10 out of 40)

In other words, 8 years ago, 1 out of every 4 children involved in an automobile accident died (25%).

Fast forward 8 years later:

Total # serious accidents: 120 (up 20%, according to the stimulus)
Proportion of accidents involving young children: 40% (remains the same, according to (B))
# serious accidents involving children: 48 (40% of 120)
# of young children killed: 11 (up 10%, according to the stimulus)
Proportion of young children killed in serious accidents: about 23% (11 out of 48)

Since the proportion of accidents involving children remained the same, we see that now a smaller percentage of children die in the accidents in which they are involved (23% today vs. 25% 8 years ago).

Hope that helps!

Best,
Kelsey
eyeofthetiger
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Hi team,

I'm having trouble simply narrowing down the options to contenders, let alone picking an answer for this question. I think the crux is that I don't understand the relationship between the 20% rise in serious automobile accidents and the 10% rise in children killed riding in cars. I think that once I understand their relationship, I'll be able to narrow down the answer choices and see which one strengthens the argument (the conclusion of which is that the doubled use of auto safety seats for children 4 and under has prevented child fatalities that would have otherwise occurred.)

Any thoughts would be greatly appreciated.
Robert Carroll
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tiger,

The author's argument is that the increased use of automobile safety seats by children aged 4 and under has prevented child fatalities that otherwise would have occurred. Supporting that conclusion is the premise that the number of children 4 and under killed in automobile accidents rose 10 percent, while the total number of serious automobile accidents rose 20 percent.

At first sight, it doesn't look like that premise helps the author - more children were killed, so how could the seats have helped? The key is the author's comparison of percentages - if the number of serious accidents went up 20 percent, but the number of children killed went up 10 percent, the number of children killed increased by a smaller percentage. If 20 percent more accidents, you'd expect 20 percent more fatalities, so a 10 percent increase might show that the safety seats helped. However, because these percentages are of different things (20 percent increase in the accident total vs 10 percent increase in fatality total), we can't compare the two numbers without more information.

It's helpful to consider a situation that matches the facts (the percentage increases) but doesn't support the author's argument. Say that serious accidents increased by 20 percent, but those increased serious accidents all involved adult drivers driving alone and colliding with other adult drivers driving alone. In other words, the 20 percent increase involved many more accidents occurring that did not involve children aged 4 or under. If that were true, then the fact that fatalities among such children went up 10 percent would weaken the author's argument - accidents not involving children went up, but more children were involved in fatal accidents.

To Strengthen the argument, we need to know the opposite - instead of the 20 percent increase being unrepresentative and involving a population that excludes children 4 and under, if the 20 percent increase did nothing to chance the distribution of young children in serious accidents, then we're be comparing apples to apples - 20 percent increase in serious accidents WOULD mean 20 percent more children involved, so a 10 percent increase in fatalities would be unusually low. Thus, we would have reason to think the author was right about something making children safer, including the safety seats that were used more frequently in the same 8-year period. As this is a Strengthen question, such new information is acceptable in an answer choice.

I hope this has enabled you to evaluate the answer choices better, but if the correct answer is not clear now I can follow up. Let me know!

Robert
eyeofthetiger
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Thank you, Robert. Posing that hypothetical situation really helps underline what we need to strengthen the argument.

I'm curious - is this a method that should be used in general with strengthen questions? Or was it simply a tool to help me understand what to look for? I'm a bit concerned that while reviewing the correct answer, it didn't seem to strengthen the argument to me, but while I used this method, it became easier.

Thanks
Lucas Moreau
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Hello, tiger,

I would say this is a good general method for Strengthen questions. A lot of LSAT answers don't seem intuitive the first time around - all correct answers are genuinely correct, but that doesn't make them easy. ;) Using hypotheticals like these can help you understand the answers. I like to think of it as coming at the question from multiple angles, thinking about it several different ways, to see if I can make it come together in my head. If you find this works, keep on doing it! :-D

Hope that helps,
Luke
eyeofthetiger
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Definitely. Thanks!
Lsat180Please
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Can you please discuss why C is incorrect? Also how would you recommend attacking this question on an actual test? I loved your explanations but I know I would not have time to do all that math on the actual exam. Thank you!
Ben DiFabbio
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Lsat180Please wrote:Can you please discuss why C is incorrect? Also how would you recommend attacking this question on an actual test? I loved your explanations but I know I would not have time to do all that math on the actual exam. Thank you!


Hey there,

Answer choice C) doesn't quite strengthen the argument for two reasons that I can see: First, the fact that "children" are taking more trips in cars doesn't tell us how old those children are--maybe the increase was only among children aged 5 and up. Second, it's not clear how taking more trips would put them at a greater risk of a serious accident, since the average total time they spent in cars remained constant.

As for the "real time" reasoning process, I wouldn't say you need to do any math at all! The important thing to notice about the argument is just that it depends on a certain "number and percentage" relationship to apply equally to the the premises and to the conclusion.

The argument can be distilled like this:
P1. MORE children under 4 are using safety seats now than they were 8 years ago.
P2. The total number of children under 4 who were killed in accidents over the last 8 years INCREASED LESS than the number of serious accidents overall.
Conclusion: The increased use of safety seats prevented child fatalities that otherwise would have occurred.

The logic goes, since the number of child fatalities was lower than would be expected based on the increase in serious accidents overall, then the safety seats must have saved some lives. In order to reach that conclusion, we need to know that the PROPORTION of children involved in serious accidents didn't significantly decrease for some reason. Answer choice B) assures us that the proportion remained the same, so the conclusion follows.

I hope that helps!

- Ben