As mentioned by the researchers, one problem they did not account for was the fact that conduct disorder has a high comorbidity with attention deficit disorder with hyperactivity. They had no measure of hyperactivity or of attention deficit. The study by Robins looked at whether conduct disorder alone led to criminal activity or if it had an indirect effect instead. Using data from the Epidemiological Catchment Area project he set out to answer a number of questions related to predictors of criminal behavior. This would make generalizing the results outside of Sweden difficult.
Some results are similar in both such as higher levels of criminal activity in men than women.
In order to see if one supports the finding of the other it would be important to determine if they are in fact measuring the same thing. It is also important to remember that the purpose for each study was also slightly different. If it is found that the studies are measuring similar things then it adds to the ability to generalize the results since the populations studied were quite different. They used a combination of peer nominations, teacher ratings, self reports and parent reports. However, after removing arrests for alcohol abuse they found no correlation for girl's level of aggression and criminal convictions.