Baseball has always been a favorite pastime in America and is rife with statistics and theories. In a recent paper, researchers showed that major league players who have nicknames live 2½ years longer than those without them (The Wall Street Journal, July 16, 2009). You do not believe in this result and decide to collect data on the lifespan of 30 baseball players along with a nickname variable that equals 1 if the player had a nickname and 0 otherwise. The accompanying table shows a portion of the data; the complete data set, labeled Nicknames, can be found on the text website.

YearsNickname

74........1

62........1

: ........ :

64........0

a. Create two subsamples consisting of players with and without nicknames. Calculate the average longevity for each subsample.

b. Specify the hypotheses to contradict the claim made by researchers at Wayne State University.

c. State the conclusion of the test using a 5% level of significance. Assume the population variances are unknown but equal.