9Variance of Evidence II
As I wrote at the end of Chapter 6, “the uncertainty due to variance (
) is incorporated into various statistical formulas.” Notice how the “trick” formula incorporates variance.
Recall that when 
gets either smaller or larger than 0.5, then the proportion variance 
gets smaller. In the “trick” formula, the term 
is in the numerator, and so as 
decreases or increases from 0.5, then the standard error 
decreases and so margin of error decreases. As variance decreases, uncertainty decreases and the confidence interval can narrow its focus.
You can see this in ...
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