数理统计——生物统计学的数学基础

Population Mean:if a population contains N entities whose measures are x1,x2, … xN, the arithmetic mean is given by

Sample Mean: if a sample collected from apopulation contains n observations: x1, x2, … xn, the sample mean is given by

Population or sample median (M or   ) is defined as the observation  whose depthis d = (N+1)/2 or d = (n+1)/2:

Range: the difference between the largest and smallest observationsin a group of data;

Variance: average of squared deviates of each observation from mean of observations in a group of data.

It is easy to show that and