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