Last month a random sample of 1000 subjects was interviewed and asked whether they thought the president was doing a good job. This month the same subjects were asked this again. The results are: 450 said yes each time, 450 said no each time, 60 said yes on the first survey and no on the second survey, and 40 said no on the first survey and yes on the second survey.
a. Form a contingency table showing these results.
b. Estimate the proportion giving a favorable rating
(i) Last month
(ii) This month.
c. Show how each of the proportions in part b can be obtained as a sample mean.
d. Find the test statistic and P-value for applying McNemar’s test that the population proportion was the same each month. Interpret.