The DSM IV was a more conservative revision requiring that changes be justified by a high threshold of scientific evidence drawn from literature reviews , data reanalyses , and field testing .
The earlier DSM revisions had relied on expert opinion to create definitions of disorders .
The DSM   was a more conservative DSM requiring that changes be justified by a high threshold of scientific evidence drawn from literature reviews , data reanalyses , and field testing .
The earlier DSM revisions had relied on expert opinion to create definitions of disorders .