Tools
Practice, not just reading
Each of these exists because a chapter needs it. They run in the browser, need no account, and use the same R packages the course cites.
DAG builder
Draw a causal graph and get the adjustment sets back. Checks d-separation, marks colliders, and flags the variables that open a path rather than closing one.
R playground
Run R in the browser against the NHEFS dataset the course uses, so any example in a chapter is one you can edit and rerun without leaving the page.
Calculators
Eleven of them: E-value, bias factor, misclassification, selection bias, probabilistic bias analysis, propensity overlap, IPW diagnostics, SMD balance, NNT, sample size and effect conversion.