#14- The number of serious traffic accidents (accidents

[chian9010]

Hello, SLF,

E is not the best answer choice for this question. The term "serious accidents" is defined at the beginning of the stimulus, and there is no indication that its meaning drifted at all over time. (Besides, if E is right, does that mean that accidents that caused immediate death aren't serious?! )

C is better, since it is providing an alternate cause for the conclusion asserted. For Weaken questions like this one, you're not just trying to disprove the conclusion: you're trying to show that the stated premise(s) do(es) not lead to the conclusion.

In this case, the assertion is that the lowered speed limit was the cause of the lowered rate of serious accidents. If C is true, however, then that provides a significant possible alternate cause for the conclusion asserted - and that would weaken the argument more than any other of the answer choices.

Hope that helps,
Lucas Moreau
PowerScore

I now understand why C is correct but I am still confused why E is not correct. For this kind of weaken question, the answer choice can surely add extra information as a support. For me, I think E is exactly the kind of example. Yes, according to the stimulus, the author indeed defines what serious traffic accidents are. However, no one says the answer choice cannot change/modify the definition to make its own argument strong. Right?

As Lucas mentions that "if E is right, does that mean the accidents that caused immediate death aren't serious"? I know it doesn't make any sense but what if that's really answer choice E mean? It modifies the definition so it indeed can be counted as an alternative cause.

Please help me figuring out why E is not right!

[Brook Miscoski]

chian,

(E) strengthens the argument instead of weakening it. (E) states that until 1986 accidents were considered serious only if they resulted in an extended hospital stay. That means that the criteria loosened after 1986. So the second time period, when there are fewer serious accidents, is actually including more kinds of accidents as serious (anything involving a hospital stay, not just an extended stay). That would tend to strengthen the argument by indicating that even when more types of accidents are included from the later period, there are still fewer accidents in that later period.

[Alisahoban]

Answer choice e says until 1986 meaning that the categorization up until 1986 potentially undercounted the number of accidents - this would not affect the decrease in accidents that occurs, if anything if this answer were true it would mean there was actually a higher number of accidents than previously thought in the time up until they changed the speed limit

[Adam Tyson]

Exactly right, Alisahoban! That's why E doesn't hurt the argument, and why it might even help it.

This is sort of a shell game answer of something that would have hurt tremendously - what if the definition of a serious accident became MORE restrictive in 1986? If so, then it's possible that the changed definition, rather than the reduced speed limit, might be responsible for the appearance of fewer serious accidents. A classic alternate cause in the form of altered reporting standards (or you could say that is an attack on the data underlying the causal argument - it works as both).

Well done!

[PhillBugajski]

I'm still unsure as why C is correct:

C. The annual number of vehicles using Park Road decreased significantly and steadily from 1981 to 1990.
If the number decreases steadily during the entire time period, wouldn't that imply that any reduction of cars using the road would be reflected proportionately per year of the number of accidents reported?

It would make sense to me if there was a sudden drop-off of cars using the road in or after 1986, because there would be fewer, and fewer of them getting into accidents. Since the decrease is consistent across all the years, however, wouldn't a sudden drop of 35% imply that something other than the constant decrease of cars caused the decrease in serious accidents?

Conversely, I picked D because if the number of non-serious accidents remained constant, then the speed limit didn't affect the number of accidents. That leads to an alternate cause for the reduction in serious accidents, such as "cars safety measures advanced after 1986, so many accidents that would have been serious did not require a hospitalization.

Sorry if that isn't clear, but any explanation would be greatly appreciated!
Thanks,
Phill

[KelseyWoods]

Hi Phill!

The stimulus doesn't tell us that the drop in serious accidents was sudden. It just tells us that there were 35% fewer serious accidents between 1986 and 1990 than there were between 1981 and 1985. But we have no idea what happened in each individual year between 1986 and 1990. It's not saying that each year had 35% fewer serious accidents. It's saying that the total number of serious accidents within that 5 year period was 35% lower than the total number of serious accidents within the previous 5 year period.

Based on the premises, this is possible:

# of serious accidents per year
1981: 20; 1982: 20; 1983: 20; 1984: 20: 1985: 20; Total # 1981-1985= 100
1986: 0; 1987: 10; 1988: 40; 1989: 15: 1990: 0; Total # 1986-1990 = 65

But this is also possible:
# of serious accidents per year
1981: 20; 1982: 20; 1983: 20; 1984: 20: 1985: 20; Total # 1981-1985= 100
1986: 17; 1987: 15; 1988: 13; 1989: 11: 1990: 9; Total # 1986-1990 = 65

All we know is that the total number of serious accidents between 1986 and 1990 is lower than the total # of serious accidents between 1981 and 1985 but those accidents could be distributed between the five years in each of those periods in any variety of ways. They could have reduced steadily, or maybe not. We can't assume that it was a sudden drop off or a gradual one based on the information we've been given.

Answer choice (D) doesn't lead to an alternate cause. It's just telling us that the number of non-serious accidents remained the same. But if the number of non-serious accidents remains the same and the number of serious accidents is going down (which we know from the premises in the stimulus), the overall total number of accidents would still be decreasing.

For example:

1981-1985 # of non-serious accidents: 100
1981-1985 # of serious accidents: 100
1981-1985 total # of accidents: 200

1986-1990 # of non-serious accidents: 100
1986-1990 # of serious accidents: 65
1986-1990 total # of accidents: 165

In this scenario, the total number of accidents went down because, even though the number of non-serious accidents stayed the same, the number of serious accidents decreased. This could still be due to the reduction in the speed limit. The reduction in the speed limit could have prevented some non-serious accidents from ever occurring and could have prevented some accidents that would have been serious from being less serious (being rear-ended by someone going 35 mph would do less damage than being rear-ended by someone going 65 mph). So the speed limit reduction could still explain the reduction in serious accidents.

Hope this helps!

Best,
Kelsey

[Gumbattle]

Why E is WRONG and C is CORRECT.

Since C and E are both forming situations that the serious accidents is cause by a decline in some sort of percentage,
C > less people occur, so less serious accident could happened
E > less people that originally were serious problem were not serious problem after 1985, so less serious accident happened
I have no idea why C is the right answer while E is wrong.

[Hanin Abu Amara]

E is wrong because, while we might have changed the classification of what is a serious accident, we don't know that the accidents that occurred didn't meet the old definition or the new definition. Maybe all the accidents before 1986 still resulted in hospital stays. E doesn't weaken the argument because if we distill the argument down to decrease speed limit leads to decrease in serious accidents we didn't attack the cause aka, that it wasn't the speed limit.

C is correct because it gives us an alternative reason for the decrease. It's not the decrease in speed, its the decrease in people.

Hope that makes sense