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Chapter 22

Terms in this set (5)

Variances of independent random variables add
The variance of a sum or difference of independent random variables is the sum of the variances of those variables
Sampling distribution of the difference between two proportions
The sampling distribution of p1-p2 is, under appropriate assumptions, modeled by a Normal model with mean and standard deviation
Two-proportion z-interval
A two proportion z-interval gives a confidence interval for the true difference in proportions in two independent groups
Two-proportion z-test
Test the null hypothesis =) by referring the statistic to the standard Normal model
Pooling
When we are have data from different sources that we believe are homogeneous, we can a better estimate of the common proportion and its standard deviation. We can combine, or pool, the data into single group for the purpose of estimating the common proportion. The resulting pooled standard error is based on more data and is thus more reliable ( if the null hypothesis is true and the groups are truly homogeneous)
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