Confidence Intervals for Mean (σ Known or n>30) and Sample Size

Normal distribution can only be used to find confidence intervals for the mean when:

• When the variable is normally distributed and population standard deviation ( σ ) is known.
• When  σ is unknown, sample size must be greater than or equal to 30 and use sample standard deviation (s) instead of  σ .

                    One aspect of inferential statistics is estimation

Estimation - the process of estimating the value of a parameter from information obtained from a sample.

D. Bertiz