empath is a similarity analysis of the heavy-metal bands listed in the Encyclopaedia Metallum (as of 27 July 2010), based solely on reviewer overlap. The overlap must be at least 2, and the scores are approximately the percentage of overlap, adjusted to reduce the effects of both high popularity and small samples. The lists are cut off at 30 or a minimum score of 0.03, whichever comes first. 3264 bands qualify. The bigger the band's name in the index, the more similarities it has.
 
All displayed precision is for entertainment only; no statistical significance is asserted. Aesthetic judgments are probably implied, but not mine.