symbol for sample mean.

What is the X Bar formula?

A parameter is a number that summarizes data from a population, while a statistic is a number that summarizes data from a sample. Therefore, x-bar is a statistic since it is the mean of a sample. The standard formula for the mean, or x-bar, for an ungrouped data set is: ¯¯¯x=∑ni=1xin x ¯ = ∑ i = 1 n x i n .