Enter the total variance and the mean of the set into the Calculator. The calculator will evaluate the Index of Dispersion. 

Index of Dispersion Formula

IOD = V / m


  • IOD is the Index of Dispersion ()
  • V is the total variance
  • m is the mean of the set

To calculate Index of Dispersion, divide the total variance by the mean of the set.

How to Calculate Index of Dispersion?

The following steps outline how to calculate the Index Of Dispersion.

  1. First, determine the total variance. 
  2. Next, determine the mean of the set. 
  3. Next, gather the formula from above = IOD = V / m.
  4. Finally, calculate the Index of Dispersion.
  5. After inserting the variables and calculating the result, check your answer with the calculator above.

Example Problem : 

Use the following variables as an example problem to test your knowledge.

total variance = 2.5

mean of the set = 60