1. Confidence Intervals for a Population Proportion Excel

2. CI for proportions in excel 1.Get your data set and insert a pivot table to calculate a frequency distribution for your variable of interest. 2.From the pivot table obtain the sample size (n) 3.From the pivot table obtain the sample proportion you need (p) 4.Decide on the confidence level you need (95% or 99%) 1.For 95% confidence Z=1.96 2.For 99% confidence Z= 2.57 5.Use the formula to calculate the Margin of error and then the CI.

3. CI for a proportion Formula: CI = This part is called the Margin of Error The Margin of Error tells you “how far you may be from the population proportion for the degree of confidence you chose”

4. Research Question. What percentage of CHHS students “strongly agree” with the statement “I like statistics?” We have sample data, but the research question is about the population so we need to create a confidence interval for our estimate. We want to be 95% confident of our results.