This report provides an overview of eight experiments on covariation judgment training. Included are a literature review, rationale, and description of the rule-analytic approach used in all experiments. Experiment 1 identified undergraduates' understandings of rule use, finding self-report a poor method for diagnosing sources of error. Experiment 2 identified sources of individual differences in rule use. Undergraduates were not significantly different in mathematical background, aptitude, or interests, but sex differences were found. Experiment 3 expanded the introduction and simplified question syntax with young students. Experiment 4 used young students to explore a training paradigm for rule use, finding the comparative aspect of judgment a key obstacle to rule use. Experiment 5 investigated undergraduates' judgment of response-outcome correlation using a sum-of-diagonals rule; training was effective. Experiment 6 studied methods of information presentation to undergraduates, finding that presentation conditions affected judgment. Undergraduates showed marked judgment differences, depending on sampling period, in experiment 7. The final experiment found little improvement when undergraduates added summary information to line-interval judgments. (JM)