1
$\begingroup$

How is "lift" computed? i was reading about "Gain and lift charts" in data science.

I picked the following example Data from https://www.listendata.com/2014/08/excel-template-gain-and-lift-charts.html

I am clear on how the gain values are computed. Not clear about lift values are computed? (last column in table)

$\endgroup$

1 Answer 1

2
$\begingroup$

Lift is computed by comparing performance with a random selection model. I'll explain with your example below,

  1. assume that we didn't have any statistical/ML model for ranking/scoring the respondents.
  2. In that case assume we did a random ordering of respondents.
  3. A decile (10% of total population) is expected to have 10% of the respondents. In your case, there should've been (approximately) 488 respondents in 2500 cases.
  4. But after ordering the cases by score, you are seeing 44.71% of the cases in first decile against expected 10% (in random/no model case). This gives the gain of 44.71/10 = 4.471.
  5. For next decile, cumulatively you have covered 20% of the cases. You'd expect a random/no model scenario covers 20% of the respondents. But using scores, we covered 80% of them. That gives a cumulative lift of 80/20 = 4.
$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct.

Not the answer you're looking for? Browse other questions tagged or ask your own question.