title: Extracting meaning and direction from twin data.
abstract: This paper reviews the current status of the twin method as a research tool in psychiatry. It is shown that the common practice of reporting only probandwise concordance rates leaves much of the meaning unextracted from the data, and that by including appropriate estimates of the population risk, the concordance rates can be converted into liability correlation coefficients, which can be assessed within the theoretical framework of multifactorial-threshold-polygenic disorders.
mesh_terms: D000437:Alcoholism / Q000235:genetics; D001714:Bipolar Disorder / Q000235:genetics; D003417:Criminal Psychology; D004200:Diseases in Twins; D005260:Female; D005828:Genetics, Population; D006801:Humans; D008297:Male; D008423:Maternal Age; D001523:Mental Disorders / Q000235:genetics*; D008957:Models, Genetic; D011247:Pregnancy; D012107:Research Design / Q000592:standards; D012306:Risk; D012559:Schizophrenia / Q000235:genetics; D014429:Twins, Dizygotic; D014430:Twins, Monozygotic