Good outside resources

Where a good free book or guide already exists, this site links to it rather than rebuilding it. Ten of them, one line each on what it is good for and when to reach for it. All free, no courses to buy.

Last checked: October 2026

Python and pandas

Statistics and inference

Economics with code

Machine learning

Causal inference

Practice

Every link was opened in October 2026 and pointed at the resource named. Links go stale; if one does not, let me know. Nothing here is paid or sponsored. For how these fit the jobs you are aiming at, see Careers with AI; for the skills each lab needs, see Labs and skills.