# How can I use confidence intervals for the population mean µ?

##### 1 Answer

Where

[ If your sample size is greater than 30 then the limits are given by

#### Explanation:

Calculate the sample mean (

If you assume a normally distributed population of i.i.d. (independent identically distributed variables with finite variance) with sufficient number for the central limit theorem to apply (say

The confidence interval is then:

Where

If you know the population standard deviation and do not need to estimate it (

[

z = critical value

SE is standard Error

SE =

Upper limit of the population --

Lower limit of the population -

If your sample size is less than 30 use the 't' value]