Chapter Summary

Chapter 8

The goal of most research is to find population parameters.The major objective of sampling theory and statistical inference is to provide estimates of unknown parameters from sample statistics.

Researchers make point estimates and interval estimates.Point estimates are sample statistics used to estimate the exact value of a population parameter.Interval estimates are ranges of values within which the population parameter may fall.

Confidence intervals can be used to estimate population parameters such as means or proportions.Their accuracy is defined with the confidence level.The most common confidence levels are 90%, 95%, and 99%.

To establish a confidence interval for a mean or a proportion, add or subtract from the mean or the proportion the product of the standard error and the Z value corresponding to the confidence level.