Loan origination decisions based on multiple scores with application to installment loan portfolio selection
The loan origination decision problem is that of deciding whether or not to accept a borrower's application for a loan. Lenders are increasingly adopting broader business objectives that extend beyond a single period of risk control. This trend points to the need for a more sophisticated loan origination decision framework designed to take advantage of a collection of scores, each of which predicts a different event of interest associated with the loan (e.g., default, prepayment, bankruptcy).
This dissertation presents an analytic framework for loan origination decision making using multiple scores. I establish both statistical and utilitarian metrics for measuring the performance of multiple-score systems. I provide an analytical exploration of the conditions under which an additional score provides new information that can be the basis for improved loan origination decision making. I also study the factors that affect the magnitude of the economic value brought in by the new score. I study optimal decision policies when multiple scores are used. I present a simple cutoff policy in the form of a derived score that can significantly simplify the loan origination decision with multiple scores and up to two objectives. As an application of my theory on multiple-score decisions, I address an installment loan origination decision problem in which default and prepayment predictions (scores) are available. The multiple-outcome framework has the characteristic that it provides the decision-maker with a clear vision of the entire future risk spectrum, rather than the risk at a particular epoch in time. Consequently, the multiple-score framework yields a decision that dominates that of the single-score system in business performance objectives of interest. Finally, I address ways in which variance of portfolio profit may be considered input to the origination decision. I present an analytic model to calculate the variance of portfolio profit by assuming that the performances of two individual accounts are conditionally independent given the same economic conditions. I show that considering variance in origination decisions yields a more conservative decision policy, assuming that the decision policy is based on a predetermined cutoff score.
0796: Operations research