A point estimate provides a single plausible value for a parameter. However, a point estimate is rarely perfect; usually there is some error in the estimate. Instead of supplying just a point estimate of a parameter, a next logical step would be to provide a plausible range of values for the parameter.
In this section and in Section 2.9, we will emphasize the special case where the point estimate is a sample mean and the parameter is the population mean. In Section 2.11, we generalize these methods for a variety of point estimates and population parameters that we will encounter in Chapter 3 and beyond.