The three little bears strived to get it just right, and AI model builders strive to do the same thing when it comes to specifying their model. Underspecification is when you build a model that performs well on your data, but so do other models, which could lead to your model decaying over time. The discussion of underspecification kicked off last fall when Google researchers published a paper on the subject, "Underspecification Presents Challenges for Credibility in Modern Machine Learning." "ML models often exhibit unexpectedly poor behavior when they are deployed in real-world domains. We identify underspecification as a key reason for these failures," stated the paper, put together by a group of scientists led by author Alexander D'Amour, a research scientist with Google Brain of Cambridge, Mass.