title: Holzinger's Hc revised.
abstract: The formula H'C = 1 - CDZ/CMZ is suggested as a better summary of twin concordance data than the familiar Holzinger concordance formula, HC = (CMZ - CDZ)/(1 - CDZ). The new formula better estimates degree of genetic determination, G, as calculated from a threshold model, but never exceeds unity, as G sometimes does. For high concordance rates, if CMZ + CDZ greater than 1, HC may be more useful than either G or H'C.
mesh_terms: D005260:Female; D005787:Gene Frequency; D006801:Humans; D008957:Models, Genetic; D011247:Pregnancy; D013223:Statistics as Topic; D014427:Twins