Summary
Most people who invest don’t do their own research. Of this group, some rely on their broker and others on instinct. A minority of people who invest conduct their own research. Of this group, some occasionally do their own research, while others always do their own research. Most people (of all those who invest) make a profit.
Notable Valid Inferences
Less than half of the people who invest in the stock market do their own research. Some people who don’t do their own research make a profit.
A
Some people who make a profit on their investments in the stock market do so without doing any research of their own.
This must be true. If most people who invest don’t do any research, and most people who invest also profit, there must be some people who belong to both groups. In other words, there must be overlap, as both groups encompass more than half of all people who invest.
B
Most people who invest in the stock market either rely solely on their broker or make decisions based merely on hunches.
This could be false. Most people who invest don’t do their own research; of this majority, some rely on their broker and others on hunches. There could be a third sub-group that relies on something other than a broker or hunches. We can’t assume these are the only sub-groups.
C
Some people who do investment research on their own, while just as often relying on their broker or on hunches, make a profit in the stock market.
This could be false. We don’t know how large the group of people who do some research while also relying on brokers or hunches is, but we do know they belong to the minority of people who do their own research. They could also be in the minority who don’t profit.
D
Most people who invest in the stock market without doing any research of their own make a profit.
This could be false. We know some people who invest without doing research make a profit—we have no reason to believe most of them do.
E
Most people who rely solely on their broker rather than on hunches make a profit in the stock market.
This could be false. We know most people who invest don’t do their own research: within this group, some people make a profit and some rely solely on their broker. We don’t know if these groups overlap and how many people (if any) who rely solely on their broker make a profit.
A
there may be many forms of dangerous radiation other than X-rays and the kinds of radiation absorbed by members of commercial airline flight crews
Other forms of dangerous radiation are irrelevant. The author is only concerned with the dangers of radiation from commercial airline flights and dental X-rays.
B
receiving a dental X-ray may mitigate other health risks, whereas flying does not
Whether X-rays or flights may mitigate other health risks is irrelevant. The argument only focuses on the dangers of radiation put out by flights and X-rays.
C
exposure to X-rays of higher intensity than dental X-rays may be harmful
Higher-intensity X-rays are irrelevant. The argument is only concerned with the radiation put out by dental X-rays and flights.
D
the longer and the more often one is exposed to radiation, the more radiation one absorbs and the more seriously one is harmed
The author fails to consider this. If members of commercial flight crews go on a lot of flights, the low levels of nearly harmless radiation they absorb on each flight could eventually add up and harm them.
E
flying at high altitude involves risks in addition to exposure to minor radiation
Risks posed by altitude are irrelevant. The author just argues that radiation from commercial flights poses little danger to commercial flight crews.
Summarize Argument
The author concludes more funding should be directed toward intervention research in order to explore a cost-effective way to help people predisposed to mental disorders. Why? Because more research is needed to confirm some existing research—which found that early intervention can mitigate risk factors for mental disorders—and to develop practices for care based on those results.
Notable Assumptions
The author assumes the care practices developed will be cost-effective while addressing risk factors for mental disorders. She assumes more funding for intervention research will be directed towards the “comprehensive research program” described, that more funding is required for such a program, and that such a program is necessary to confirm the findings of the limited research.
A
Most minor mental disorders are more expensive to treat than other minor health problems.
This doesn’t affect the argument. The author implies a comparison between the cost of treating early risk factors for mental disorders and the cost of treating more-fully-developed mental disorders, not between minor mental disorders and other, unrelated health problems.
B
Prevention research can be coordinated by drawing together geneticists, neurologists, and behavioral scientists.
This explains how the research program might be organized, not why it’s necessary to confirm the results of the existing research. It’s possible the previous research also included input from geneticists, neurologists, and behavioral scientists.
C
Reducing known risk factors for mental disorders is relatively inexpensive compared to the long-term treatment required.
This makes concrete the author’s main assumption, that treating risk factors early is more cost-effective than treating full-blown disorders later. It justifies her advocacy for funding in order to develop those treatments.
D
Current funding for intervention research is now higher than it has ever been before.
This compares past funding with present funding, while the author compares present funding with future funding. She argues funding should increase to support the program described—she makes no claim about the present level of research funding relative to past levels.
E
Once a mental disorder disappears, there is a fair chance that it will recur, given that complete cures are rare.
This doesn’t affect the argument. There’s no indication that current care practices or the ones to be developed will cause mental disorders to disappear—only that they might help prevent those disorders from developing.