With headlines claiming “Study Shows Gun Control Works,” media outlets such as CBS, MSNBC, PBS, Washington Post, and BBC were breathless over a soon-to-be-released study by Daniel Webster in the Journal of Urban Health. The claim is that when Missouri in 2007 made it easier to buy handguns, the murder rate went up relative to the U.S. murder rate.

Prior to August 2007, Missouri law had established what is known as a universal background check, closing down the so-called gun show loophole.

While it is true that the murder rate in Missouri rose 17 percent relative to the rest of the U.S. in the five years after 2007, it had actually increased by 32 percent during the previous five years. The question is why the Missouri murder rate was increasing relative to the rest of the United States at a slower rate after the change in the law than it did prior to it. Missouri was on an ominous path before the law was ended.

Simply looking at whether murder rates were higher after the law was rescinded than before misses much of what was going on. Most likely, getting rid of the law slowed the growth rate in murders.

But there are other reasons not to accept the conclusion touted by the press.

The reason for this cherry picking is obvious. Only those conditions produced the desired results. For example, Missouri’s violent crime rate fell 7 percent faster than the violent crime rate for the rest of the United States from 2006 to 2012.

Researchers should not cherry pick one state to examine. Consider the following. You flip a coin 20 times — ten heads and ten tails. If you specifically picked just five heads, you might well conclude the coin was biased. Since most readers don’t know the data, researchers need to make clear why they are only examining a small portion of the total sample.

There is already ample research on these universal background checks across all the states. Indeed, the third edition of More Guns, Less Crime provided one study on this, and, unlike the Webster study, it shows no reduction in murder rates from these expanded background checks. Indeed, there was even a slight 2 percent increase in murder rates, but the result was not statistically significant.

For those interested, a discussion of the other problems with Webster’s study is available here.

If one wants to look at the impact of licensing, again there is national research, again such as More Guns, Less Crime, on all sorts of licensing rules from licenses to carry a gun to licenses to own one. For example, if you wanted to look at what happened in one state where murder and robbery rates soared after gun licensing was imposed, look at the disaster that happened in Massachusetts.

It is presumably too much to hope that reporters will understand empirical work. But alarm bells should always go off when only one example is studied when many places have adopted the same types of laws. Reporters should always ask themselves why that one state was examined. Why didn't the researcher even look at what happened when the law was adopted?

Unfortunately, the Webster study isn't alone. There have been a rash of recent news stories on other misleading studies funded by Michael Bloomberg as well as on the risks of guns in the home.

It would be nice if there were easy fixes to keep guns away from criminals. But when gun laws primarily disarm the law-abiding, as Missouri’s permitting system used to do. Crime gets worse. Webster’s study actually provides yet more evidence that is true.