9.2 - Estimating a Population Mean

Learning Objectives: 1. Obtain a point estimate for the population mean 2. State properties of Student’s t-distribution 3. Determine t-values 4. Construct and interpret a confidence interval for a population mean 5. Determine the sample size needed to estimate the population mean within a specified margin of error

Recall that the confidence interval has the form:

point estimate ± margin of error

Recall that the sample mean is the point estimate of the 

population mean.

The exact standard deviation of the sample mean (aka ithe standard error) is

If the standard deviation of the sample mean (standard error) and we assume the population is normal, then we can use this formula (with small n):

T or F: In practice, we don’t know the population standard deviation

True.