1. Chapter 10 Inference on Two Samples 10.3 Inference About Two Population Proportions

5. Step 1. A claim is made regarding two population proportions. The claim is used to determine the null and alternative hypothesis. The hypothesis can be structured in one of three ways. NOTE: p 1 is the assumed value of the population proportion for population 1 and p 2 is the assumed value of the population proportion for population 2.

11. Step 4: Compare the critical value with the test statistic:

12. Step 5: State the conclusion.

16. EXAMPLEFinding a Confidence Interval for the Difference between Two Population Proportions An economist obtains a random sample of 800 urban households and finds that 338 of them have Internet access. He obtains a random sample of 750 rural households and finds that 292 of them have Internet access. Find a 99% confidence interval for the difference between the proportion of urban households that have Internet access and the proportion of rural households that have Internet access.

18. EXAMPLE Determining Sample Size A doctor wants to estimate the difference in the proportion of 15 - 19 year old mothers that received prenatal care and the proportion of 30 - 34 year old mothers that received prenatal care. What sample size should be obtained if she wishes the estimate to be within 2 percentage points with 95% confidence assuming (a) she uses the results of the National Vital Statistics Report results in which 98.0% of 15-19 year old mothers received prenatal care and 99.2% of 30-34 year old mothers received prenatal care. (b) she does not use any prior estimates.