Hector Yee works at Airbnb developing machine learning models using their open-source ML stack Aerosolve. He has developed complex models in Spark to predict demand for Airbnb listings. His models for pricing recommendations consider numerous features like location, listing quality, seasonality and events to predict booking probabilities. The models are interpretable using techniques like controlled feature engineering and quantization, and regularization helps prevent overfitting of high-capacity models.