Decile lift
Also known as: Lift · Lift chart · Gain (lift) · Lift by deciles
How many times a score group concentrates more events than the average of the base. A lift of 1.8x in the worst decile means the 10% with the worst scores have 1.8 times the event rate of the whole portfolio.
Legal basis
Wikipedia — Lift (data mining)
To read lift, the base is ordered by the score and cut into groups — typically deciles, ten slices of 10%. In each slice you compare that slice's event rate with the average rate of the whole base. The ratio between the two is the lift.
The lift of the worst decile is the number a risk operation cares about most: it is the strength of the score where it has to be strong, at the end that concentrates claims and default. A lift of 1.8x there means the 10% with the worst scores go bad 80% more often than the average — that is where the decision to decline, reprice or review acceptance lives.
Frequently asked questions
What is lift in the worst decile?
It is how many times the event rate of the 10% with the worst scores exceeds the average rate of the base. A lift of 1.8x means 80% more events than the average in that group.