# Chapter 11: Inference on Two Samples

In Chapters 9 and 10, we studied inferential statistics (confidence intervals and hypothesis tests) regarding population parameters of a single population - the average rest heart rate of students in a class, the proportion of ECC who voted, etc.

In Chapter 11, we'll be considering **the relationship between two populations** - means, proportions and standard deviaions. One frequent comparison we want to make between two populations is concerning the proportion of individuals with certain characteristics. For example, suppose we want to determine if college faculty voted at a higher rate than ECC students in the 2008 presidential election. Since we don't have any information from either population, we would need to take samples from each. This isn't an example of a hypothesis test from Section 10.4, about one proportion, it'd be comparing two proportions.

If you're ready to begin, just click on the "start" link below, or one of the section links on the left.