On consumer lending :
The most creditworthy customers, it turns out, are the least keen to splurge when extra credit is offered. For every dollar their credit limits increase, they boost their borrowing by $0.23. Even that is an exaggeration: by further digging through the data, the researchers establish that the borrowers with the best credit records are only shifting their borrowing from card to card to take advantage of improved terms—not borrowing any more in aggregate. At the other end of the scale, those with the muckiest credit histories borrow an extra $0.58 for every $1 hike in their credit limit.
But that is not the whole story. The researchers then take a bank’s perspective, and ask to whom it makes most sense to lend. Boosting credit limits draws in extra interest payments and charges, but there are costs too. If it is mainly the highest-risk borrowers who take advantage of higher limits, or if the higher limits encourage more reckless borrowing in general, then default rates will climb, eating away at profit margins.