Cluster correlation.

Correlation between individual clustering measures of pain rating and the magnitude of the placebo analgesia, or the expectation of analgesia (parameter w) estimated by the model on placebo data. Subjects’ pain ratings were clustered with the K-means method for 2 clusters, whereas bimodal vs unimodal distribution was assessed with Bayesian hypothesis comparison. Cluster distance: distance of the cluster centers; Separation index: cluster separation index; Prob. bimodality: probability that the data follow a bimodal distribution; r: Pearson’s product moment correlation coefficient, tested for positive correlation. (n = 31). (See also Fig. 6B).Cluster correlation.