solution

19.  
Estimation: When you have selected the t-statistic and the theory-based
overlay, you can also use this applet for estimating the parameter of interest.
(You can also go directly to the Theory-Based Inference applet which will also
allow you to change the confidence level.) Check the box next to 95% CI(s) for
difference in means.

a. Identify, in words related to
the context of this study, the relevant parameter to be estimated here.

 b. Report the 95% confidence
interval for this parameter.

c. Does the 95% confidence
interval calculated from the GSS sample data contain the value 0? What does
that imply? (Hint: Recall that a confidence interval is an interval of
plausible values for the parameter of interest, and the interval is calculated
using the sample statistics.)

d. Does the 95% confidence
interval agree with your conclusion in #16? How are you deciding?

 e. Fill in the blanks of the
sentence below to complete the interpretation of the 95% confidence interval:
We are _______% confident that the mean number of close friends men have is
___________ than the mean number of close friends that women have, by between
________ and _______ friends. f. How would the width of the interval change if
you increased the confidence level to 99%? Why?

 g. How would the width of the
interval change if you increased the sample size? Why?

 h. How would the width of the
interval change if the variability of the number of close friends increased for
both males and females? Why?