4.3.A—Interpret a confidence interval in context for a population mean or population mean difference

Interpret a confidence interval in context for a population mean or population mean difference.

• Because the confidence interval for a population mean or population mean difference is calculated based on a sample from a population, the computed interval may or may not contain the value of the population mean or population mean difference.
• The interpretation of the confidence level is as follows: In repeated random sampling with the same sample size from the same population, approximately C% of confidence intervals created will capture the population mean or population mean difference, where C represents the numerical value of the confidence level used.
• When interpreting a C% confidence interval for a population mean or population mean difference, we say we are C% confident the interval ()ab, contains the value of the population mean or population mean difference, where a represents the lower limit and b represents the upper limit. An interpretation of a confidence interval for a population mean or population mean difference includes a reference to the parameter.