The Ash Twins Blog

Computer Scientist Panos Ipeirotis writes that

An interesting example of a company deriving policy based on their predictive model is American Express. They realized that the feature “customer buys in a 99c store” is correlated with higher delinquency rates. So, AmEx decided to decrease the credit limit for such customers. Of course, the result will be that potentially affected customers will stop visiting such stores, decreasing the value of this policy for AmEx. Furthermore, this action may cause even more economic stress to these customers that are now “forced” to buy from more expensive stores, and this may result in a much higher default rate for AmEx. This “unexpected” outcome is the effect of devising policy based on non-causal variables.