Chapter 22

Question 1

Variance of independent random variables add

Answer 1

The variance of a sum or difference of independent random variables in the sum of the variances of those variables.

Question 2

Sampling distribution of the difference between two proportions

Answer 2

The sampling distribution of (P hat)p1-p2 is, under appropriate assumptions, modeled by a Normal model with mean and standard deviations.

Question 3

Two-proportion z-interval

Answer 3

Gives a confidence interval for the true difference in proportions, p1-p2 in two independent groups.

Question 4

Pooling

Answer 4

When we have data from different sources that we believe are homogeneous, we can get a better estimate of the common proportions and its standard deviation. We can combine the data into a single group for the purpose of estimating the common proportion.

Question 5

Two-proportion z-test

Answer 5

test the null hypothesis HO:p1-p2=0 by referring the statistic to a standard Normal model.