An Introduction to Machine Learning for the Pediatric Hospitalist.

Machine learning models are increasingly used in clinical research to predict patient outcomes, yet many clinicians lack the training to critically appraise these studies. This article provides a conceptual introduction to machine learning for the pediatric hospitalist with no prior computational experience. We focus on the most common application in clinical medicine: supervised learning, where models learn from data with known outcomes to make predictions about new unseen patients. Core tasks such as classification and regression are explained, along with intuitive models like decision trees and advanced methods like ensembles. Essential concepts for critical appraisal, including overfitting and leakage, the challenge of interpretability, and data bias, are highlighted. We emphasize the importance of model validation and the distinction among prediction, interpretation, and causation. The article concludes by deconstructing a published pediatric study to illustrate these principles in practice, equipping the reader to better understand and evaluate research that uses machine learning. Our goal is to equip pediatric hospitalists with the foundational knowledge to become informed consumers and potential contributors within the machine learning ecosystem, ensuring that this technology augments, rather than replaces, clinical judgment.