Chapter 12 Inference for Proportions AP Statistics 12.2 – Comparing Two Population Proportions

Conditions for 2-proportion Inference Both samples were collected by an SRS. Samples are Independent of each other. Both populations are at least Ten times the sample. The distribution of is approximately normal for large sample sizes:

Comparing 2 Population Proportions (Note: proportions use Z – Procedures) We compare population difference by using sample differences Confidence Intervals: Significance Tests: z-statistic:

Construct a 95% CI:

Common Practice Comparative Studies –Start w/ 1-sample  divide into 2 groups based on data 2-sample z procedures for comparing population proportions are valid in these situations.

Pooled Sample Proportion We don’t pool the sample proportion in OUR calculations, but the calculator does, so you must do the z-statistic by hand!