"Cluster randomized trials," in which groups of patients are randomly assigned to different therapeutic interventions, provide a powerful way of evaluating drugs. CRTs have not been widely used, in good part because of concerns about whether patients must give informed consent to participate in them. A better understanding of how CRTs fit into clinical practice resolves the concerns.
Girotto and Legrenzi's 1993 facilitation effect for their SARS version of Wason s THOG problem a disjunctive reasoning task was examined. The effect was not replicated when the standard THOG problem instructions were used in Experiments 1 and 2. However, in Experiment 3 when Girotto and Legrenzi's precise instructions were used, facilitation was observed. Experiment 4 further investigated the role of the type of instructions in the observed facilitation. The results suggest that such facilitation may result from attentional factors rather (...) than the use of a combinatorial analysis in the problem. (shrink)