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Question Weighting in Knowledge-Based Authentication (KBA): Part 1

— by, Andrew Gulledge

The intelligent use of question weighting in KBA should be a no-brainer for anyone using out of wallet questions. Here’s the deal: some authentication questions consistently give fraudsters a harder time than other questions. Why not capitalize on that knowledge?

Question weighting is where each question type has a certain number of points associated with it. So a question that fraudsters have an easier time with might be worth only 50 points, while a question that fraudsters often struggle with might be worth 150 points. So the KBA score ends up being the total points correct divided by the total possible points. The point is to make the entire KBA session more punitive for the bad guys.

Fraud analytics are absolutely essential to the use of intelligent question weighting. While fraud prevention vendors should have recommended question weights as part of their fraud best practices, if you can provide us with as many examples as possible of known fraud that went through the out of wallet questions, we can refine the best practice question weighting model to work better for your specific population.

Even if we keep your pass rate the same, we can lower your fraud rate.On the other hand, we can up your pass rate while keeping the fraud rate consistent. So whether your aim it to reduce your false positive rate (i.e., pass more of the good consumers) or to reduce your fraud rate (i.e., fail more of the fraudsters), or some combination of the two, question weighting will help you get there.