Since most of the social behavioural problems, cannot be subjected to experimental investigations, ex-post factor research is a good explanatory instrument of changes that take place in the dependent variables. If the set of independent variables is carefully selected and proper techniques adopted for analyses, meaningful insights can be gained into the changing pattern of dependent variables.
It can even be said that ex-post facto research is more important than experimental research. This is, of course, not a methodological observation. It means rather, that the most important social scientific research problems do not lend themselves to experimental, although many of them do lend themselves to controlled inquiry of the ex-post facto kind.