In answering the following exercises, it will be helpful to have before you the definitions of Type I and Type II errors that you have already learned. Here is a reminder:

Type I: There really is not an effect (population truth), but you find one (your decision) in your study.

Type II: There really is an effect (population truth), but you don’t find one (your decision) in your study.

People who have infectious mononucleosis (“mono”) test positive for the virus on a heterophile test of sheep cell agglutination. A man who does not have mono but is merely tired and nursing a cold takes the diagnostic test, and the test result is positive. What type of error is this false positive—is it Type I or Type II? Explain your answer.