# 9.9: Introduction to Estimate the Difference Between Population Proportions


## What you’ll learn to do: Construct and interpret confidence intervals to compare two population/treatment group proportions.

In this section we will learn to construct a confidence interval to estimate the difference between two population proportions (or the size of a treat-ment effect) when conditions are met. We will then interpret the meaning of a confidence level associated with a confidence interval. This is important when we describe how the confidence level affects the margin of error. We will then evaluate whether conclusions are reasonable when given the description of a statistical study.