A research study revealed that, in most cases, once existing highways near urban areas are widened and extended in an attempt to reduce traffic congestion and resulting delays for motorists, these problems actually increase rather than decrease.

"Surprising" Phenomenon
Why do traffic congestion and delay problems increase after widening and extending highways in urban areas?

Objective
The correct answer should suggest a difference between having wider, more extended roads and having less wide, less extended roads. This difference should create the potential for more congestion when roads are wider and more extended.

A
Widened and extended roads tend to attract many more motorists than used them before their improvement.
Wider, more extended roads could lead to more congestion by attracting a lot more drivers. This effect could more than outweigh whatever decrease in congestion the physically wider roads create.
B
Typically, road widening or extension projects are undertaken only after the population near the road in question has increased and then leveled off, leaving a higher average population level.
We’d still expect wider roads to lead to less congestion. Maybe these projects only occur in highly-populated areas; wider roads can still allow people to drive more freely and with less delays.
C
As a general rule, the greater the number of lanes on a given length of highway, the lower the rate of accidents per 100,000 vehicles traveling on it.
It’s not clear how the accident rate relates to congestion and delay.
D
Rural, as compared to urban, traffic usually includes a larger proportion of trucks and vehicles used by farmers.
The discrepancy involves urban areas. A comparison to rural areas doesn’t explain why wider, more extensive roads in urban areas leads to more congestion.
E
Urban traffic generally moves at a slower pace and involves more congestion and delays than rural and suburban traffic.
The discrepancy involves urban areas. A comparison to rural areas doesn’t explain why wider, more extensive roads in urban areas leads to more congestion.

7 comments

A study found that consumers reaching supermarket checkout lines within 40 minutes after the airing of an advertisement for a given product over the store’s audio system were significantly more likely to purchase the product advertised than were consumers who checked out prior to the airing. Apparently, these advertisements are effective.

Summarize Argument: Phenomenon-Hypothesis
The author concludes that ads aired at supermarkets are effective. He supports this with a study showing that consumers who checked out within 40 minutes of hearing an ad were more likely to buy the product than those who checked out before the ad aired.

Notable Assumptions
The author assumes that there are no alternative hypotheses that explain the correlation between customers hearing the ad and purchasing the advertised product. He assumes customers weren't already planning to buy the product and that the increase in purchases isn’t just a coincidence. He also assumes that the study reflects the effectiveness of all supermarket ads.

A
During the study, for most of the advertisements more people went through the checkout lines after they were aired than before they were aired.
Irrelevant. The argument addresses whether people were more likely to buy the product, not how many people bought the product. So it doesn’t matter when more people checked out.
B
A large proportion of the consumers who bought a product shortly after the airing of an advertisement for it reported that they had not gone to the store intending to buy that product.
This rules out the alternative hypothesis that most customers who bought an advertised product were already planning to buy it that day. This makes it more likely that the ad influenced their purchase.
C
Many of the consumers reported that they typically bought at least one of the advertised products every time they shopped at the store.
This doesn’t help to establish that the advertisement itself caused people to buy the product. Also, (C) doesn’t say which consumers reported buying an advertised product every time they shop— maybe the consumers in (C) didn’t even hear the ad.
D
Many of the consumers who bought an advertised product and who reached the checkout line within 40 minutes of the advertisement’s airing reported that they could not remember hearing the advertisement.
Irrelevant. Whether people remember hearing the ad doesn’t tell us whether they actually heard it. If they didn’t hear it, this would weaken the conclusion that the ad influenced their purchase.
E
Many of the consumers who bought an advertised product reported that they buy that product only occasionally.
Irrelevant. The fact that people only buy the product occasionally doesn’t explain whether the ad influenced their purchase on this occasion. They might have already planned to buy it that day.

12 comments

In a study of patients who enrolled at a sleep clinic because of insomnia, those who inhaled the scent of peppermint before going to bed were more likely to have difficulty falling asleep than were patients who inhaled the scent of bitter orange. Since it is known that inhaling bitter orange does not help people fall asleep more easily, this study shows that inhaling the scent of peppermint makes insomnia worse.

Summarize Argument: Phenomenon-Hypothesis

The author hypothesizes that inhaling the scent of peppermint makes insomnia worse. She bases this on the observation that patients with insomnia who inhaled the scent of peppermint before bed were more likely to have difficulty falling asleep than patients who inhaled the scent of bitter orange, which doesn’t help people fall asleep more easily.

Notable Assumptions

The author assumes that inhaling peppermint directly causes difficulty in falling asleep, without considering alternative explanations and other factors.

She also assumes that the only difference between the two groups is the scent they were exposed to, without considering other possible differences that could influence the outcomes.

She also assumes that the study was conducted properly and that the study’s sample is representative of all insomnia sufferers.

A
Several studies have shown that inhaling the scent of peppermint tends to have a relaxing effect on people who do not suffer from insomnia.

The study and the author’s conclusion are only addressing the effects of inhaling the scent of peppermint on people who do suffer from insomnia. So the effects on people who do not suffer from insomnia is irrelevant.

B
The patients who inhaled the scent of bitter orange were, on average, suffering from milder cases of insomnia than were the patients who inhaled the scent of peppermint.

The author assumes that the only difference between the two groups is the scent they inhaled, but (B) shows that those who inhaled bitter orange already had milder insomnia than those who inhaled peppermint. This weakens the conclusion that peppermint worsens insomnia.

C
Because the scents of peppermint and bitter orange are each very distinctive, it was not possible to prevent the patients from knowing that they were undergoing some sort of study of the effects of inhaling various scents.

We don’t know that the patients’ knowledge of the study affected their ability to fall asleep, or why it would have affected one group’s ability but not the other’s. (C) also doesn’t address the author’s conclusion or assumptions.

D
Some of the patients who enrolled in the sleep clinic also had difficulty staying asleep once they fell asleep.

The study and conclusion are only about the effects of the scents on falling asleep. Whether patients stayed asleep is not relevant.

E
Several studies have revealed that in many cases inhaling certain pleasant scents can dramatically affect the degree to which a patient suffers from insomnia.

This could mean that inhaling certain pleasant scents can make insomnia worse or that it can make it better. We also don’t know what qualifies as a “pleasant scent” here. (E) is simply too vague to apply to the author’s conclusion about this specific study.


13 comments

Dogs learn best when they are trained using both voice commands and hand signals. After all, a recent study shows that dogs who were trained using both voice commands and hand signals were twice as likely to obey as were dogs who were trained using only voice commands.

Summarize Argument
Dogs learn best when trained with both voice commands and hand signals. How do we know? In a recent study, dogs trained with both methods were twice as likely to obey instructions compared to dogs trained with only voice commands.

Identify Argument Part
The referenced text is the conclusion. The rest of the argument supports the claim by citing a study.

A
It is an explicit premise of the argument.
The referenced text is a conclusion. Premises, such as the one about the study, support conclusions.
B
It is an implicit assumption of the argument.
If it’s referenced text, it can’t be an implicit assumption! The referenced text is very explicitly the argument’s conclusion.
C
It is a statement of background information offered to help facilitate understanding the issue in the argument.
It’s not background information. It’s a claim that requires support, which the author provides in the form of a recent study.
D
It is a statement that the argument claims is supported by the study.
The referenced text is a supported claim, or in other words, a conclusion. The author supports her claim about dogs learning best with both hand signals and voice commands by citing a recent study. This works!
E
It is an intermediate conclusion that is offered as direct support for the argument’s main conclusion.
There’s only one conclusion in the argument—that dogs learn best with both hand signals and voice commands, which is exactly what the referenced text says.

1 comment

Scientist: Any theory that is to be taken seriously must affect our perception of the world. Of course, this is not, in itself, enough for a theory to be taken seriously. To see this, one need only consider astrology.

Summarize Argument
The scientist concludes that, while a theory must affect our perception of the world to be taken seriously, that alone isn’t sufficient to take a theory seriously. The scientist points to a supporting example—astrology.

Identify Argument Part
The scientist mentions astrology to provide support for her conclusion, which is that a theory shouldn’t be taken seriously simply because it affects our perception of the world. Evidently, the scientist thinks astrology affects our perception of the world, but shouldn’t be taken seriously for other reasons.

A
an example of a theory that should not be taken seriously because it does not affect our perception of the world
The scientist implies that astrology does affect our perception of the world. She uses it as an example precisely because it affects our perception of the world while nevertheless being a theory that we shouldn’t take seriously.
B
an example of something that should not be considered a theory
The scientist never says astrology shouldn’t be considered a theory. She implies it shouldn’t be taken seriously.
C
an example of a theory that should not be taken seriously despite its affecting our perception of the world
Sure, astrology affects our perception of the world—a necessary condition for a theory to be taken seriously. But the scientist still suggests astrology shouldn’t be taken seriously, presumably for other reasons.
D
an example of a theory that affects our perception of the world, and thus should be taken seriously
The scientist doesn’t believe astrology should be taken seriously, hence why she uses it as an example. Affecting perception is a necessary condition for a theory to be taken seriously, but not a sufficient one according to the argument.
E
an example of a theory that should be taken seriously, even though it does not affect our perception of the world
The scientist doesn’t believe astrology should be taken seriously, though she does believe it affects our perception. This is why she uses astrology as her example.

4 comments