I have estimation of mean / confidence level problem with very litte data
to go on ie no Std Dev, no population infor etc..
The unknown is the sample "n" - how large should it be?
The problem is what percentage of apples at a farm have bruises on them?
Only facts are confidence level 95% and error of estimate +/- 4% - Given
this how do you calculate n?
There is a formula which dispenses w/the need for a standard deviation (they
cancel out), when E is expressed as a fraction of the standard deviation.
ex.
N = (confidence coefficient * standard deviation / E)^2
N = 1.96 * SD / SD/5
= 1.96 * 5
My book gives examples, but no practical knowledge of how to convert an
error of estimate into a fraction of a standard deviation?
Thus how would +/- 4% be represented as a fraction of one or more standard
deviations?
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