Question: Let us compare the distribution of the number of lifetime gifts of those who made a current donation to that of those who did not. We will use two data sets, each indicating the number of gifts (lifetime gifts, previous to this mailing) given by the 20,000 people represented in the donations database (on the companion site). One data set is for those who did not make a donation in response to this mailing (named "gifts_D0" with 19,011 people), while the other is for those who did (named "gifts_D1" with 989 people).
a. Find the average and standard deviation for each data set. Compare and interpret these values.
b. Compare these averages and standard deviations to the average and standard deviation of the lifetime gifts for the full database of 20,000 people.