A study of adults who suffer from migraine headaches revealed that a significant proportion of the study participants suffer from a complex syndrome characterized by a set of three symptoms. █████ ███ ██████ ████ ███ ████████ ███████████ █████████ ███████ ██████ █████ ██████████ ██ ████████████ █████ ██████ █████ ████████████ ████████ ██████████ ██ █████ ██████ ██████████ ███ ███ ██ ███ ████ ████ █████ ██ ██████████ █████████ █████ ██ ███████████ █████ ████ ███████ ██ ██████████ ██████ ████ █████████ ███████ ██ ███ ██████████ ██ ███████ ████ █████████ ███████ ██ █████████ ██ ███ ██ ███ ██████ ██ ████████ █████████ ███ ██████████ ██ █████ █████
The stimulus begins by describing the results of a study focused on adults suffering from migraine headaches. The study found that many of these adults suffered from a syndrome with three symptoms: first, excessive anxiety in childhood; second, migraines in adolescence; and third, bouts of depression beginning around age 20.
After providing this context, the author notes that this pattern of three symptoms is invariable and always starts with excessive anxiety in childhood. From this premise, the author hypothesizes that such anxiety must be a cause of migraine headaches and depression in later life.
The major flaw here is that the author describes a correlation — for people with this syndrome, these three symptoms always occur, with anxiety occurring first — and concludes a causal relationship: because anxiety occurs first, it must cause the other two symptoms.
This doesn't have to be true. Just because the symptoms always show up in a particular order doesn't mean they cause each other in that order. Maybe all three symptoms are caused by some genetic factor that manifests in different ways at different ages. In that case, the three symptoms wouldn't be causing each other, so much as sharing one cause.
The reasoning in the argument ██ ██████████ ██ █████████ ██ █████ ███ ██ ███ █████████ ████████
It does not ███████ ███ ██████████ ██ █████ ██ ███ ███████ ██████████ ███ ██████ ████ ███ █████████
This doesn't matter. The author's hypothesis is only about people who suffer from this syndrome, not about any other group. The author never makes any claims that would require him to show how much of the general population suffers from the syndrome. However many sufferers of this syndrome there are, we know there are at least some, and the author is offering a hypothesis for why they exhibit the symptoms they do.
It fails to ████ ███ ███ ███████████ ████ ███ ██ ███ ██████████████ ████████ ██ ███ ████████ ████ █ ██████ ██████
This is correct. The author assumes causation from a correlation, without ruling out the possibility of alternative causes: for instance, that all three symptoms are caused by some other factor, rather than one symptom — anxiety — causing the other two.
It makes a ██████████████ ████ ██ ████████████ ████ ███ █████████
Incorrect. The author's hypothesis isn't inconsistent with the evidence. The evidence provided is just a correlation that doesn't necessarily favor a particular explanation: these three symptoms occur in a particular order, with anxiety coming first.
On its own, this evidence is perfectly consistent with the author's conclusion that anxiety causes the other two symptoms. The problem is that the evidence is also perfectly consistent with other explanations, such as a fourth factor causing all three symptoms. The fact that the author doesn't rule out such explanations is the real flaw in the argument.
It fails to ███████████ ████ ███ ██████ ███ ████████████ ██ ███ █████ ███ ██████████████ ██ ████████ ██████████
Irrelevant. This would be a problem if the author's hypothesis said that anxiety caused migraines for all migraine sufferers. But nothing in the argument makes a claim about all migraine sufferers. The focus is only on people suffering from the syndrome the author identifies.
So even if the study is an unrepresentative sample of migraine sufferers in general, we're not interested in that group as a representation of all migraine sufferers. The study sample as a whole is only relevant because it reveals that some people suffer from the particular syndrome the author is interested in.
It does not █████████ ███ ███ █████ ██ ████████ █████████ ███ ██████████ ██ █████ █████████████
Irrelevant. We're told from the outset that the study is focused on "adults who suffer from migraines." The point of the study is to find out the causes of migraines in adults, not of migraines in children or adolescents. This doesn't need to be justified.