class-imbalance
2 free lessons tagged class-imbalance across AI. Each one is a short sequence of focused steps with narration and a five-question quiz at the end — take them in any order, no signup required.
Classification: Logistic Regression and Metrics That Do Not Lie
A classifier outputs a score; you choose where to cut it. Learn how logistic regression and log loss work, why 99% accuracy can be worthless on rare events, how precision, recall and PR curves expose it, and how to pick a threshold from the real costs of each mistake.
Why Reported Order Book Results Do Not Replicate
At a one-event horizon, 92 percent of mid-price labels are exactly no-change, so a model that always predicts flat scores 92 percent accuracy. This lesson computes that baseline across horizons and works through the four mechanisms that turn a genuine measurement into a number nobody can reproduce.