In a survey of introductory statistics students, an instructor asked her students to report how many Facebook friends they had. Suppose that the intent is to study whether there is an association between number of Facebook friends and a person€™s sex.

a. Identify whether the study is an experiment or an observational study. Explain.
b. Identify the observational units.
c. Identify the explanatory and response variables. Also, for each variable identify whether it is categorical or quantitative.
d. Which of the following is the appropriate null hypothesis? Circle one.

A. There is an association between a person€™s sex and the number of Facebook friends.
B. Th ere is no association between a person€™s sex and the number of Facebook friends.
C. On average, men have more Facebook friends than women.
D. On average, men have fewer Facebook friends than women.

e. Which of the following is the appropriate alternative hypothesis? Circle one.
A. There is an association between a person€™s sex and the number of Facebook friends.
B. Th ere is no association between a person€™s sex and the number of Facebook friends.
C. On average, men have more Facebook friends than women.
D. On average, men have fewer Facebook friends than women.

Here are a few summary statistics about the data:

f. In this context, which of the following is an (are) appropriate statistic value(s) to compare men to women? Circle all that apply.
A. 35 ˆ’ 13 = 22
B. 594.30 ˆ’ 405.60 = 188.70
C. 532 ˆ’ 485 = 47
D. 309.80 ˆ’ 228.40 = 81.40
Suppose that we want to use cards to carry out a randomization test of the appropriate hypotheses.
g. How many cards will we need? Circle one.
A. 35 

B. 13
C. 48 

D. Doesn€™t matter

The following is output from carrying out the randomization test using the Multiple Means applet.

h. On the histogram above, shade the region that depicts the p-value.

Transcribed Image Text:

Sample Sample Sample Sample mean median size SD Women 594.30 532 35 35 309.80 Men 13 228.40 405.60 485 Mean = 0.170 Mean 15.007 SD = 97.891 SD = 101.098 40 50 100 80 150 120 200 160 250 200 -400 -200 200 400 -400 -200 200 400 Shuffled differences in means Shuffled differences in medians Count Count