Ian Wong, co-founder of Opendoor, shares what he’s learned about machine learning and data science in his work as CTO of Opendoor and helping detect fraud at Square. We talk about the differences between descriptive and predictive ML, approaches to human-in-the-loop prediction, setting up a data science org to deliver real business impact, why so many internal tooling projects fail, and how leaders should be dividing their attention between top-level strategy and the details that really matter.