Q1 - In 1974 the speed limit

[jimmy902o]

how is this question different from question 23 in section 1
(of this same test)?

observed phenomenon: decreased fatality rate after speed limit reduced

conclusion (explanation for why phenomenon occurred) : the reduction saved lives

doesn't B strengthen the argument by ruling out the possibility that a decline occurred in a following year? I am also still confused about what D means and what role it plays in argument. any clarification would be appreciated

[maryadkins]

You're right about the core:

after speed limit reduction, fatality rate dropped immediately, then kept dropping over the next 10 years

-->

the SL reduction saved many lives

The assumption is that there isn't another reason(s) why the fatality rate fell. (D) strengthens the core by giving us evidence that when people drive over the SL, the fatality rate is higher.

(A) weakens the argument, if anything. (Fewer people were on the roads, and maybe that's why the fatality rate fell.)

(B) is irrelevant. Maybe it just leveled off 12 years later, but it had fallen for the previous 10 years. That seems like still a pretty good argument.

(C) also weakens the argument; maybe people are living because of the seat belts.

(E) is irrelevant. So? What does this do to the argument?

You're right that Section 1, Q23 is similar in that it's ultimately asking you to strengthen the argument and (D) does so by eliminates a competing explanation for the discrepancy. But other than that, so I'm not sure what you mean.

Hope this helps. Please let me know if you need more clarification!

[Mab6q]

Let me take a stab at this one.

Conclusion: the drop in the speed limit saved many lives


WHY: the speed limit was reduced to 55, and after one year the rate of highway fatalities dropped by 15 %, and over the next ten years it dropped another 25 percent.

Looking at this core, I noticed two problems:

1. the author seems to be playing with percentages. Just because the percentages went down, it doesn't mean more lives were saved. It could be that the drop in the speed limit led to many more people driving, so even though we had a drop in the rate of fatalities, more people were dying each year.

2. author mistakes correlation for causation.

Just because the drop in speed limit coincided with the drop in the rate of fatalities, it doesn't mean the two are related. It could be that something else, such as a national campaign to promote better driving, was the cause.

To strengthen the first issue, we have to show that the number of people driving did not increase to such an extent whereby we could not conclude that many lives were saved.

To strengthen the second issue, we have to rule out the possibility that some other factor caused the drop. It's important to note that when we are given correlation/causation flaws on Strengthen and Weaken questions, the answer choice usually tests our understanding of this. So it is likely that we will be tested on the second issue.

A. this was very tempting for me at first because it seems to get at our first issue. That there was no increase in driving. However, if that's that case, it would provide an alternative cause for the drop in fatalities, so it can't be correct.

B. is irrelevant because we don't know anything about the 12th year. Maybe the speed limit was increased again.

C. gives us an alternative cause, which means it would weaken the argument.

D. gives us a classic way to strengthen a correlation flaw on the LSAT - by showing that when you don't have the cause, you won't get the effect.

55mph --> lower rate

D: don't have 55mph --> rate is not as high

This strengthens our correlation and is the correct answer.

E. not impact on argument.