The percentage of units in a population that possess a specified property. For example, the percentage of a given collection of registered voters who are registered as Republicans. If each unit that possesses the property is labeled with "1," and each unit that does not possess the property is labeled with "0," the population percentage is the same as the mean of that list of zeros and ones; that is, the population percentage is the population mean for a population of zeros and ones. The population percentage is a parameter. See sample percentage.