When an AI model's accuracy declines despite stable input distributions, the most likely cause is concept drift—where the underlying relationship between inputs and the target variable changes over time. In credit scoring, this may occur when economic conditions, consumer behavior, or risk patterns shift in ways not captured in the original training data.
Why C is Correct: The ISACA AAIR model drift guidance identifies concept drift as the greatest risk in this scenario because it means the model is making credit decisions based on relationships that no longer hold in the current environment. Faulty credit decisions can lead to incorrect denials of creditworthy applicants, incorrect approvals of high-risk applicants, regulatory violations, financial losses, and harm to individuals—all high-severity consequences for a credit-scoring application.
Why A is Wrong: Technical delays in credit score updates are an operational performance concern. Delays create business friction but do not cause the fundamental accuracy problem described in the scenario.
Why B is Wrong: Underfitting from shortened training cycles is a model development quality issue. The scenario specifies stable input distributions and declining accuracy—characteristic of drift, not underfitting, which would manifest differently.
Why D is Wrong: Increased retraining costs represent a financial efficiency concern. While budgetary impacts are real, they are secondary to the risk of faulty credit decisions affecting individuals and regulatory compliance.
