Population Stability Index(PSI)

Population Stability Index

For each bin:

$$PSI_i = (Actual\% - Expected\%)\times \ln(Actual\% / Expected\%)$$

Total:

$$PSI = \sum(PSI_i)$$

Result:

PSI	Value Inference
<= 0.1	Insignificant change
0.1 – 0.25	minor change
> 0.25	Major shift in population