county data. The Statistical Abstract of the United States and the Current Population Survey provide an extensive supply of social, economic, and vital statistics at the county, state, and local levels. Use their Web sites to compare state data to national data in the following way.

a. Choose a variable of interest that involves a mean for a particular state (for example, the mean household size in Illinois).

b. Find the current national value for that variable (for example, the national mean household size).

c. Choose a particular county within the state and obtain the corresponding data for the county, as well as the sample size (for example, the mean household size in Cook County, Illinois).

d. Assuming that the county is a random sample of the state, test the claim that the state is above or below the national level in terms of that variable.

e. Discuss and interpret your results. The hypothesis test depends on the sample (the county) being a random sample of the population (the state). Be sure to discuss this factor in your conclusions.