# "Estimate of standard error of the proportion"

Please provide a proof/explanation of this formula. I'm particulary confused why $p ^\prime q ^\prime$ is in the numerator.

$$\sigma_{p} = \sqrt \frac{p ^\prime q ^\prime}{n}$$
This is to the confidence interval for $p$.

• Are you okay with standard formula definition of standard error ??

• Yes.

• And clarify this is for population or sample ?

• Sample.

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• Why does $V(X{i}) = E(X{i}^2) - E(X{i})^2$?
• That is a standard way to compute the variance of a variable. The definition of variance is $V(X) := E( (X-EX)^2 )$ And from this definition it is not difficult to prove the formula I used. It's easy to prove it from the