Make your “Cost Per Story Point” stable. Why and how.

In his book, “Principles of Product Development Flow”, Donald Reinertsen wrote about the “Principle of Variability Pooling”:

“The Principle of Variability Pooling: Overall variation decreases when uncorrelated random tasks are combined.
Variability pooling exploits a somewhat subtle mathematical characteristic of variability. When we sum two or more uncorrelated random variables, the variance of the sum is the sum if the individual variances.”

Bringing this principle to the home-front: