Summary
The author concludes that retrospective studies can’t reliably accomplish their goal (determine causes of present characteristics) because they must use the subjects’ self-reported data.
Missing Connection
The conclusion determines that these studies aren’t reliable, but the only support for this is that they use subjects’ self-reported data. We can validly draw the conclusion if we know that self-reported data isn’t reliable.
A
Whether or not a study of human subjects can reliably determine the causes of those subjects’ present characteristics may depend at least in part on the extent to which that study uses inaccurate reports about the subjects’ pasts.
This deals with the right core elements, but isn’t strong enough. And even with a stronger rephrasing, e.g. “... subjects’ present characteristics depend on...”, it would still be wrong because 1) we were not told the reports are inaccurate, 2) we don’t know the extent.
B
A retrospective study cannot reliably determine the causes of human subjects’ present characteristics unless there exist correlations between the present characteristics of the subjects and what happened to those subjects in the past.
Irrelevant. We do not know if there are any correlations or not.
C
In studies of human subjects that attempt to find connections between subjects’ present characteristics and what happened to those subjects in the past, the subjects’ reports about their own pasts are highly susceptible to inaccuracy.
This is a direct link from retrospective studies and an unavoidable part of those studies (self-reported data) to inaccuracy. We can conclude that these studies’ determinations aren’t reliable.
D
If a study of human subjects uses only accurate reports about the subjects’ pasts, then that study can reliably determine the causes of those subjects’ present characteristics.
We are trying to conclude that the studies cannot reliably determine the cause, not that they can. Also, we don’t know if the reports are accurate or not.
E
Every scientific study in which researchers look for significant connections between the present characteristics of subjects and what happened to those subjects in the past must use the subjects’ reports about their own pasts.
The conclusion is only about retrospective studies. It isn’t about all studies that look at these connections.
Summarize Argument
It is more likely that the extra space on gigantic planes will be used for more passenger seating than shops and lounges. This is because the number of passengers flying is expected to dramatically increase, and normal-sized planes alone would not be able to accommodate all those passengers. Therefore, the extra space on gigantic planes must be utilized to carry passengers.
Identify Conclusion
The conclusion is the author’s hypothesis about what the extra space will be used for: “the additional space will more likely be used for more passenger seating.”
A
Gigantic planes currently being developed will have enough space in them to hold shops and lounges as well as passenger seating.
This is context that sets up the argument about what that extra space will actually be used for.
B
The additional space in the gigantic planes currently being developed is more likely to be filled with passenger seating than with shops and lounges.
This accurately rephrases the conclusion. The conclusion is that it is more likely that the additional space on gigantic planes will be used for passenger seating. More likely than what? The shops and lounges mentioned in the context.
C
The number of passengers flying the air-traffic system is expected to triple within 20 years.
This is support for why the extra space on gigantic planes will likely be used for passenger seating. There will be lots more passengers that need seats.
D
In 20 years, it will be impossible for airports to accommodate enough normal-sized planes to carry the number of passengers that are expected to be flying then.
This is support for why gigantic planes will likely use the extra space for seating. Regular planes alone can’t carry the passenger load because there isn’t enough space for all the planes that would be needed. Therefore, gigantic planes need to carry the extra passengers.
E
In 20 years, most airline passengers will be flying in gigantic passenger planes.
This is not contained in the stimulus. The argument is about what the space on gigantic planes will be used for, not where most passengers will be flying. We have no idea what the proportions will be.
Reporter: This means, then, that if anyone in the study had athlete’s foot that was not cured, that person did not receive medication M.
Summarize Argument
The reporter concludes that, in a study testing medications for athlete’s foot, anyone who was not cured was not given medication M. This is based on the observation that, in the study, everyone whose athlete’s foot was cured received medication M.
Identify and Describe Flaw
This is a cookie-cutter flaw: confusing sufficient and necessary conditions. In the study, everyone whose athlete’s foot was cured received medication M, making medication M necessary to have been cured in this study. However, that doesn’t mean medication M is sufficient to cure every case that it was used to treat. In other words, it’s possible that not everyone who received medication M was cured.
A
The reporter concludes from evidence showing only that M can cure athlete’s foot that M always cures athlete’s foot.
The argument confuses sufficient and necessary conditions. Only M cures athlete’s foot, making it necessary for curing athlete’s foot in the study. However, that doesn’t mean it’s sufficient to always cure athlete’s foot.
B
The reporter illicitly draws a conclusion about the population as a whole on the basis of a study conducted only on a sample of the population.
The reporter only draws a conclusion about the study, not the population as a whole.
C
The reporter presumes, without providing justification, that medications M and N are available to people who have athlete’s foot but did not participate in the study.
The reporter doesn’t make any claims about the availability of the medications, only their effects on athlete’s foot in the study.
D
The reporter fails to allow for the possibility that athlete’s foot may be cured even if neither of the two medications studied is taken.
The reporter is only drawing a conclusion about the efficacy of medication M based on the study, and doesn’t need to account for the possibility that athlete’s foot could be cured in other ways.
E
The reporter presumes, without providing justification, that there is no sizeable subgroup of people whose athlete’s foot will be cured only if they do not take medication M.
The reporter is only discussing the study, where every participant whose athlete’s foot was cured had received M. The possibility of this kind of subgroup is irrelevant to M being necessary to cure athlete’s foot in the study.