Using the data from your own survey (see Exercise 5 of Chapter 2) give 95% and 99% confidence intervals for the population mean and total.

Exercise 5 The best way to gain understanding of a sampling and estimation method is to carry it out on some real population of interest to you. If you are not already involved in such a project professionally, choose a population and set out to estimate the mean or total by taking a simple random sample. Examples include estimating the number of trees on a university campus by conceptually dividing the campus into plots, estimating the number of houses in a geographic area by selecting a simple random sample of blocks, or estimating the mean number of people per vehicle during rush hour. In the process of carrying out the survey and making the estimates, think about or discuss with others the following:

(a) What practical problems arise in establishing a frame, such as a map or list of units, from which to select the sample?

(b) How is the sample selection actually carried out?

(c) What special problems arise in observing the units selected?

(d) Estimate the population mean and total.

(e) Estimate the variance of the estimators used in part (d).

(f) How would you improve the survey procedure if you were to do it again?