Debates on gun laws have heated up again following recent mass shootings and crime surges, but either side has strong scientific evidence to fall back on, according to RAND Corporation. In a newly released report, RAND researchers suggest several statistical models to more effectively measure the effects of state gun laws, based on a years-long rigorous review. After reviewing 12,916 relevant studies published between 1995 and 2018, RAND researchers identified just 123 studies that were properly designed to show a causal relationship between gun laws and subsequent effects. Poorly designed studies often equate a correlational relationship with a causal relationship, such as claiming a state’s gun law decreased crime by simply comparing it to crime in other states without such a law. Numerous other factors, such as changes in policing or social investment, could have also been in play. Quality studies do best to explain away alternative factors, according to …