Statistic

A statistic varies from sample to sample because it depends on which individuals you happen to select. For example, if 52 out of 100 sampled voters favor a measure, the sample proportion is $\hat{p} = 0.52$ (p-hat, the estimate of the population proportion). Common statistics include the sample mean $\bar{x}$ (x-bar) and the sample standard deviation $s$. Its value changes with each new sample, which is what sampling distributions describe.