The file measles.dat contains data consistent with that obtained in a survey of parents whose children had not been immunized for measles during a recent campaign to immunize all children between the ages of 11 and 15. During the campaign, 7633 children from the 46 schools in the area were immunized; 9962 children whose records showed no previous immunization were not immunized. In a follow-up survey to explore why the children had not been immunized during the campaign, Roberts et al. (1995) sent questionnaires to the parents of a cluster sample of the 9962 children. Ten schools were randomly selected, then a sample of the Mi non-immunized children from each school was selected and the parents of those children were sent a questionnaire. Not all parents responded to the questionnaire; you will examine the effects of non response in Exercise 13 of Chapter 8.
a. Estimate, separately for each school, the percentage of parents who returned a consent form (variable returnf ). For this exercise, treat the €œno answer€ responses (value 9) as not returned.
b. Using the number of respondents in school i as mi, construct the sampling weight for each observation.
c. Estimate the overall percentage of parents who received a consent form along with a 95% CI.

estimated variance from (c) estimated variance if the data were analyzed as an SRS