The aftermath of the Newtown tragedy has seen some orgs insisting that research shows an irrefutable link between media and real-life violence, while the entertainment industry is pretty much saying just the opposite.

So what is it? Common Sense Media, the parents org, unveiled a study today that is designed to show why additional research is needed. Anyone who has followed this knows that, going back six decades, major incidents of violence have from time to time been followed by calls for scientific study. Back in the 1960s, Sen. Thomas Dodd (D-Conn.), the father of current MPAA chairman Chris Dodd, led a commission on juvenile delinquency that held numerous hearings and studies on TV violence, with the end result being pretty much inconclusive.

Yet Common Sense Media surveys the research that has been done and concludes that even though the record is ripe, it is inadequate.

“The presence of violent images in advertising seen by children has barely been studied, comprehensive research on TV violence is nearly two decades old, video game research hasn’t kept pace with current modes of gaming or tracked the content most consumed by youth, and studies of online exposure are nearly nonexistent,” its report says.

Among other things, they are calling for “longitudinal studies that include the most current media, especially the ultra-violent first-person shooter games, and the latest movies and television shows.” Longitudinal studies are those that examine a group over a period of a long time, like from age 8 to 18, which is probably why such research is so costly.

Common Sense Media’s study that even a small finding can have a significant consequences. The U.S. Surgeon General in 2001 found that “taken together, findings to date suggest that media violence has a relatively small impact on violence,” but “research to date justifies sustained efforts to curb the adverse effects of media violence on youth.”

Nevertheless, advocates for measures to limit videogame violence say that the industry will always be able to argue that there is no causal relationship, as not all children who play violent video games, watch violent cartoons or see violent movies become violent. An aide to California state Sen. Leland Yee, who authored the state’s violent videogame law, points out that tobacco companies have said the same thing among smoking, as not all smokers get lung cancer. That’s why Common Sense Media suggests that “it is probably moe accurate and useful to think about media violence as a ‘risk factor’ rather than a ’cause’ of violence — one variable among many that increases the risk of violent behavior among some children.”

The complete Common Sense Media report is here.