An article in Science News reported on a study to compare treatments for reducing cocaine use. Part of the results are short-term psychotherapy that offers cocaine abusers practical strategies for maintaining abstinence sparks a marked drop in their overall cocaine use. . . . In contrast, brief treatment with desipramine—a drug thought by some researchers to reduce cocaine cravings—generates much weaker drops in cocaine use (Bower, 24, 31 December 1994, p. 421).
a. The researchers were obviously interested in comparing the rates of cocaine use fol­lowing treatment with the two methods. State the null and alternative hypotheses for this situation.
b. Explain what the two types of error could be for this situation and what their conse­quences would be.
c. Although no p-value is given, the researchers presumably concluded that the psychotherapy treatment was superior to the drug treatment. Which type of error could they have made?