Population proportion

In statistics a population proportion, generally denoted by ${\displaystyle P}$ or the Greek letter ${\displaystyle \pi }$,^[1] is a parameter that describes a percentage value associated with a population. A census can be conducted to determine the actual value of a population parameter, but often a census is not practical due to its costs and time consumption. For example, the 2010 United States Census showed that 83.7% of the American population was identified as not being Hispanic or Latino; the value of .837 is a population proportion. In general, the population proportion and other population parameters are unknown.

A population proportion is usually estimated through an unbiased sample statistic obtained from an observational study or experiment, resulting in a sample proportion, generally denoted by ${\displaystyle {\hat {p}}}$ and in some textbooks by ${\displaystyle p}$.^[2][3] For example, the National Technological Literacy Conference conducted a national survey of 2,000 adults to determine the percentage of adults who are economically illiterate; the study showed that 1,440 out of the 2,000 adults sampled did not understand what a gross domestic product is.^[4] The value of 72% (or 1440/2000) is a sample proportion.