I have a set of data that states the volume required each month for the next 12 for 750 raw materials.
I would like to determine the variability in the demand for each material, and categorise the results into a low, medium, high format.
I have found some potential candidate statistical methods to measure this:
- Coefficient of Variation
- Interquartile Range / Median
- Median Absolute Deviation from the Median (/median)
- mean absolute deviation (/mean)
What would be the best method to determine the variability?
The data for each material may not be normally distributed; however, the same method needs to be applied to them all. In many cases the data could have quite a lot of skew.
For the advised method, please state the prerequisites to use it, the advantage it has over other methods and provide guidance on how I would interpret the results in the format stated above. FYI if you feel that there is a better measure of variability i haven't listed please feel free to suggest.
A few additional items of information that will be useful
I am using Excel to do the calculations
The chosen method and methodology for interpretation needs to be relatively simplistic as it will be adopted by people who are not statistically minded
The calculation for variability will be based on a population size of 12
The data is on a ratio scale (0 is really 0)