上游充通大 ParisTech SHANGHAI JIAO TONG UNIVERSITY INSTITUT DES SCIENCES ET TECHNOLOGIES PARIS INSTITUTE OF TECHNOLOGY Sample Problem: Simple Statistics The standard deviation is 2 Here x is the mean,x represents the ith data value and n is the number of data values. The expression (-x)is the square of the "deviation of an individual item from the mean. 8Sample Problem: Simple Statistics • The standard deviation is • Here is the mean, represents the i th data value and n is the number of data values. • The expression is the square of the “deviation” of an individual item from the mean. 8   2 1 i x x s n     x i x   2 i x x 