Causal and Statistical Reasoning
This is a free, online textbook/course that "examines the nature of causal claims and the statistical sorts of evidence used to support them."
The site contains: "1.approximately 20 content modules, 2.a repository of over 100 short case studies, and 3.a "Causality Lab" that allows students to simulate the work a social scientist does in trying to discover what causes what from data. 4.a cognitive tutor that teaches D-separation."
The site "includes self-guiding materials and activities, and is ideal for independent learners, or instructors trying out this course package."