evidence: HomeNewsAll NewsGun waiting periods could save hundreds of lives a year, study says [...] Gun waiting periods could save hundreds of lives a year, study says [...] Formica says that though the study does a good job of describing the relationship between waiting periods and gun deaths, it does have one major limitation: Because the researchers looked at population-level data and not at outcomes for individual gun purchasers, it's a bit of a stretch to say with certainty that these waiting periods actively prevented deaths. "You can't tell if gun purchasers were the ones directly affected, so you can't know for sure that it's a causal relationship," she says.