Data for: Number of cards to infer rule for placing cards into piles

Nearly sixty years ago, in a publication with a growing rate of citation ever since, JR Platt presented "strong inference" (SI) as an accumulative method of inductive inference to produce much more rapid progress than others. The article offered persuasive testimony for the use of multiple working hypotheses combined with disconfirmation. It is often cited as an exemplar of scientific practice. However, the article provides no evidence of greater efficacy. Over a 34 year period a total 780 matched trials were completed in 56 labs in a university course in statistical science. The reduction from random (18.9 cards) to selected cards was 7.2 cards, compared to a further reduction of 0.3 cards from selected to SI. In 46% of the 780 trials, the number of cards to infer a rule was greater for strong inference than for a less rigid experimental method. Based on the evidence, strong inference added little additional strength beyond that of less rigidly structured experiments.