Week 12 : Mean Deviation , Varaince and Standard Deviation

Mean Deviation:

  • A defect of the range is that it is based only two values, highest and the lowest.
  •  It does not take into consideration all of the values.
  • The Mean Deviation does take into consideration based on all values.

Variance:

  • The variance of a set of observation is defined as the mean of the squares of deviation of all the observations from their mean.
  • Variance is another absolute measure of dispersion.The variance is also denoted by Var (X).

 

Standard Deviation:

  • Standard Deviation (S.D) is the most commonly used measure of dispersion . It is a measure of spread of data about the mean.
  • Standard Deviation is a number that measures how far away each number in a set of data is from their mean.