Business Statistics

156 Business Statistics

which approximate percentage of values of the distribution are likely

to fall within a given number of standard deviation from the mean

is determined as m ± 1, that is, mean ± 1 standard deviation covers

68.27% of the items in a data set;

m ± 2, that is, mean ± 2 standard

deviation covers 95.45% of the items in a data set;

m ± 3, that is,

mean ± 3 standard deviation covers 99.73% of the items in a data

set.

Empirical rule applies only to normally distributed data. It has

a wide range of applicability but in cases where data distribution is

not normal or where the shape of the distribution is not known, its

applicability ...