Question: Explain which of the "difficulties and disasters" is most likely to be a problem in each of the following observational studies, and why:

a. A study measured the number of writing courses taken by students and their subsequent scores on the quantitative part of the Graduate Record Exam. The students who had taken the largest number of writing courses scored lowest on the exam, so the researchers concluded that students who want to pursue graduate careers in quantitative areas should not take many writing courses.

b. Successful female social workers and engineers were asked to recall whether they had any female professors in college who were particularly influential in their choice of career. More of the engineers than the social workers recalled a female professor who stood out in their minds.