Next section: Characteristics of estimators

When a parameter is being estimated, the estimate can be either a single number or it can be a range of scores. When the estimate is a single number, the estimate is called a "point estimate"; when the estimate is a range of scores, the estimate is called an interval estimate. Confidence intervals are used for interval estimates.

As an example of a point estimate, assume you wanted to estimate the mean time it takes 12-year-olds to run 100 yards. The mean running time of a random sample of 12-year-olds would be an estimate of the mean running time for all 12-year-olds. Thus, the sample mean, M, would be a point estimate of the population mean, μ.

Often point estimates are used as parts of other statistical calculations. For example, a point estimate of the standard deviation is used in the calculation of a confidence interval for μ. Point estimates of parameters are often used in the formulas for significance testing.

Point estimates are not usually as informative as confidence intervals. Their importance lies in the fact that many statistical formulas are based on them.

Next section: Characteristics of estimators