Overview of Point Estimation
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