Senators. The U.S. Congress, Joint Committee on Printing, provides information on the composition of Congress in Congressional Directory. On the WeissStats site, we present data on party and class for the senators in the 113th Congress.

a. Group the bivariate data for these two variables into a contingency table.

b. Determine the conditional distribution of party within each class and the marginal distribution of party.

c. Determine the conditional distribution of class within each party and the marginal distribution of class.

d. Are the variables “party” and “class” for U.S. senators in the 113th Congress associated? Explain your answer.

Extending the Concepts and Skills