Standard Deviation
Standard Deviation is square root of variance. It is very important because it gives variance result for same sample unit.
Properties of Standard Deviation:
In normal distribution, 68.27% of data are added between standard deviation over and under average. 95.45% of data are added between two standard deviations over and under average. 99.73% of data are added between two deviations over and under average.
See formula:
Where:
S = Standard Deviation
Xi = Salary
Sf = Frequency
N = Number of elements of sample