The percentage of a random sample with a certain property, such as the percentage of voters registered as Democrats in a simple random sample of voters. The sample mean is a statistic commonly used to estimate the population percentage. The expected value of the sample percentage from a simple random sample or a random sample with replacement is the population percentage. The SE of the sample percentage for sampling with replacement is (p(1−p)/n )^½, where p is the population percentage and n is the sample size. The SE of the sample percentage for sampling without replacement is the finite-population correction ((N−n)/(N−1))^½ times the SE of the sample percentage for sampling with replacement, with N the size of the population and n the size of the sample. The SE of the sample percentage is often estimated by the bootstrap.