One of the major applications of statistics is
estimating populationparameters
from sample statistics
. For example, a poll may seek to estimate the proportion of adult
residents of a city that support a proposition to build a new
sports stadium. This proportion is called a point
estimate of the population proportion. It is called a point
estimate because the estimate consists of a single value or point.

Point estimates are usually supplemented by interval
estimates called confidence
intervals . Confidence intervals are intervals constructed
using a method that contains the population parameter a specified
proportion of the time.