Self-study
In the past, when there was no highway speed limit, the highway accident rate increased yearly, peaking a decade ago. ██ ████ █████ ███ █████ █████ ██ ████████ ███ ███ ██ ██ ██████████ ███ ████ █████ ███ █████ ███ ██████ █████ ████ █████ ███ ████████████ ██ ███ ███████ █████ ██████ ███ ███████ ████████ ████ ███ ████ ██ █████ ██ ███████ █████ ████ ████ ██ ███ ████ █████ █████ ███████ ███ ███████ █████ █████ ██ ██ ███ ███ ████ ███ ███████ ███ ███████ ████████ ████ ██ ██ █████ ██ ████████
Summarize Argument
The author concludes that the highway speed limit has decreased the highway accident rate by at least 15 percent. This is because the highway accident rate has been at least 15 percent lower each year than it was at its peak, which came just before the highway speed limit was introduced.
Notable Assumptions
By concluding that the highway speed limit caused the reduction in accidents, the author is assuming causation from correlation. This means the author assumes there wasn't some other relevant change, like road repairs or adding new highway lanes, that happened at the same time as the speed limit was set and caused the reduced accident rate instead.
20.
Which one of the following, ██ █████ ████ █████████ ███████ ███ █████████
a
In the years █████ ██ ███ ████████████ ██ ███ ███████ █████ ██████ ████ ████ █████ ██ ██████ ████ ██ ███ ███ █████
This doesn't weaken the argument. We already know that there was no speed limit before this one was set. Knowing that the cars a decade ago were able to exceed 90kph doesn't tell us anything useful. Presumably, the cars built today are also mechanically capable of going above 90kph. None of this information tells us whether the speed limit reduced the accident rate.
b
Ten years ago, ██ █████ ██ ███████ ██ ███ ██████████ █████████ ██ ███ ████ ████████ ██ █████ ████ █ █████ █████ ██ █████ ██ ███ ███ █████
This doesn't weaken the argument. We're not interested in accidents occurring on other roads. We just want to know whether the highway speed limit is responsible for reducing the accident rate on the highway.
Illusory inconsistency
Illusory inconsistency
Answer is attractive because it seems to (but doesn't actually) contradict the premises or conclusion. In other words, it feints an attack on the premises or conclusion. If correlation is present, the answer choice is often merely an outlier datapoint, which is actually entirely consistent with the correlation.
c
Although the speed █████ ██ ████ ████████ ██ ██████████ ███ ██ ██ ███ ███ █████ ████ ██████ █████████ █████ ██████ ████ ███ █████ ██████
This doesn't weaken. Even if most people go above the speed limit, they may still be going slower than they did with no speed limit at all, in which case the speed limit might have helped improve highway safety.
Illusory inconsistency
Illusory inconsistency
Answer is attractive because it seems to (but doesn't actually) contradict the premises or conclusion. In other words, it feints an attack on the premises or conclusion. If correlation is present, the answer choice is often merely an outlier datapoint, which is actually entirely consistent with the correlation.
d
Thanks to changes ██ ██████████ ██████ ██ ███ ████ ███ ██████ ███████ ███ ██████ ████ ██ ████████ ███████ ██ █████ ████ ██ █████████ ███████████
This weakens the argument. It tells us that at the same time at the speed limit came in, there was another factor--changes in car design--that improved driving safety. So we can’t be sure it was really the speed limit that caused the 15 percent reduction in the highway accident rate.
Alternate explanation
Alternate explanation
Weaken: Introduce or support an alternate explanation for a phenomenon.
Strengthen: Helps to eliminate an alternate explanation for a phenomenon.
e
It was not █████ ███████ █████ ███ ████████████ ██ ███ ███████ █████ █████ ████ ████ ████ ████ ████████ ████ ████████ ████ ██ ████ █████ ███ ███████ ████████ ██ ███████ ████ ██ ███████████
Irrelevant. Seatbelts and airbags affect what happens after an accident occurs. We want to know about what affected the rate of accidents occurring in the first place.
Failed alternate explanation
Failed alternate explanation
Weaken Qs: Answers that try to introduce an alternate explanation, but fall short, or try to explain a different phenomenon.
Strengthen Qs: Answers that try to eliminate an alternate explanation, but fall short, or try to eliminate an explanation for a different phenomenon.