1 · The line of best fit
What OLS does, and recovering a known slope from data.
Ordinary Least Squares
The line of best fit, how it's computed, inference, and the assumptions behind it.
Course overview
Learn Ordinary Least Squares interactively
This free course uses real Python and statsmodels in your browser. Work through the modules below with explanations, executable examples, interactive controls, and questions.
2 · How OLS finds the line
The normal equations — OLS in one line of linear algebra.
3 · Inference
Standard errors, t-statistics, confidence intervals — and how they shrink with n.
4 · Assumptions & diagnostics
Gauss–Markov, heteroskedasticity, and robust standard errors.