Since Psychopaths Account for a Quarter of All Prisoners in the United

Short Answer

Since psychopaths account for a quarter of all prisoners in the United States (and for as much as 50% of all violent crime) researchers have been examining the personality traits that may play a role in this condition. Tow groups of inmates, half diagnosed by Psychiatrists as psychopathic and the other not so diagnosed were given the IRI (Interpersonal Reactivity Index as a measure of empathy). The scores, converted to T scores were as follows: Psychopaths: 35,40,28,44,45,48,42,38,40,44. Non-Pychopaths: 52,60,50,48,55,50,54,55,44,40.
-Was this experimental or post-facto research?