1. Sampling Distributions for a Proportion
AP Statistics

2. Proportions
Proportions are used to answer yes/no types of questions for populations.
The parameter is “p”.
The sample estimate is “ “.

3. Facts About
The sampling distribution of is close to normal. (z-procedures)
The mean of the sampling distribution of is the parameter p.
The standard deviation of the sampling distribution is:

4. Another Fact The standard deviation decreases as “n” increases.
To cut the standard deviation in half, quadruple the sample size.

5. Rules of Thumb
#1 - Only use the standard deviation formula of p-hat when the population is at least 10 times the sample size.
#2 - Only use the normal approximation for the sampling distribution of p-hat for values of “n” and “p” that satisfy:
These rules will become assumptions for inference and estimation.

6. Homework
Textbook: 9.22, 9.23 (skip C), 9.24, 9.27, 9.28