solution

7.      
Now you will obtain numerical summaries (statistics, such as mean and
SD) of the survey data using the Multiple Means applet.

 • Open the data fi le Close
Friends to access the raw data. Copy the data (e.g., CTRL-A and CTRL-C).

• Open the Multiple Means applet
and press clear. Click inside the Sample data box and paste (e.g., CTRL-V).
Then press Use Data.

a. Report the sample size, sample
mean, and sample SD of the number of close friends reported for each sex. Based
on the sample statistics, who tends to have more close friends, on average: men
or women? How are you deciding?

 b. Based on the sample
statistics, who tends to have more variability with respect to how many close
friends they have: men or women? How are you deciding?

c. Based on the data as presented
in Table 6.5, are the distributions of number of close friends symmetric or
skewed? If skewed, in which direction?

 d. Calculate the observed
difference in the mean number of close friends between these two groups (men
− women). (Verify your calculation by checking the Observed diff output.)

e. Notice that the value recorded
in (d) is a negative number. Well, number of friends can only be 0 or more. Why
is the number recorded in (d) less than 0?

The question we want to answer is,
Is the difference in mean number of close friends between men and women, as
seen in the GSS sample data, something that could plausibly have happened by
chance, by random sampling alone, if, on average, men and women have the same
number of close friends?