- Measures of dispersion are range, mean deviation, variance and standard deviation.
- Range = [largest value - smallest value].
- Mean deviation for an ungrouped data: MD; M.D(M)
- Mean deviation for grouped data: MD; M.D(M)
- Variance and S.D for ungrouped data:
- Variance and S.D for ungrouped data using assumed mean:
- Variance and S.D of a continuous frequency distribution:
A is assumed mean h is the common factor for all deviations.
- Coefficient of variation (C.V) = ,
- For two or more series with equal means, the series with lesser S.D is more consistent and less scattered.
- For comparision of two or more sets of data, the one which has least C.V is more consistent and less scattered