When former New York City Mayor Michael Bloomberg’s gun control groups release a report, they consistently garner massive, uncritical news coverage.  Alas. With the huge number of factual mistakes in these reports, you would think that reporters would have grown wary of pushing their propaganda.

For example, Bloomberg’s Everytown, Mothers Demand Action, and Mayors Against Illegal guns have been caught padding the number of school shootings.  While Everytown claimed 74 school shootings occurred between the Newtown, Connecticut shooting in December 2012 and June 2014, Politifact, which rated Everytown’s claim as “mostly false,” put the number of “incidents such as Sandy Hook or Columbine in which the shooter intended to commit mass murder” at 10.

Every single report released by Bloomberg’s groups has contained major errors.  A new report by the Crime Prevention Research Center has corrected Everytown’s July study on “mass shootings”: again, it is no different – lots of errors, but worldwide publicity touting the erroneous claims.

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According to this Everytown study, there were 110 mass shootings in the almost six years from January 2009 to July 2014.  But that number is heavily padded with residential killings by gangs, within family killings, or murders resulting from some other crime such as a robbery.  These murders are also important, but they are different.  What motivates a gang fight over drugs is not what motivates a Sandy Hook type mass shooter.  These mass killers plan on committing suicide.  While drug dealers are motivated by money, the public pass shooters want to kill as many people as possible so that they can get publicity. 

Mass public shootings that are not part of gang fight or some other crime are much fewer, 25, not 110.   Unfortunately, Everytown hasn’t learned from previous criticisms of their padded numbers with unrelated attacks.  

Some errors are trivial, such as getting the ages of killers wrong, but such errors reveal the sloppiness of their reports.  They entirely missed the ages of 18 killers.  They also misclassified a couple cases of stabbings as shooting deaths.

Others are more significant.  According to their July report, only 10 percent of mass shooters have a history of mental illness prior to their attacks.  Again, they simply failed to research the cases thoroughly.  Out of the 25 mass public shooting cases, they missed that five shooters had histories of clear mental illness.  Overall, 52 percent of mass public shooters had histories of mental illness.

Perhaps most importantly, the Everytown report falsely states that 86% of mass shootings occur in places where guns are allowed.  They arrive at their high figure primarily by counting attacks in private homes, which they assume allow guns.  But the debate has been about attacks

Further, as for public places, they do not correctly identify whether citizens are allowed to defend themselves.  Thus, they ignore rules that prevent general citizens from carrying guns (e.g., not acknowledging that Los Angeles County issued only 240 concealed handgun permits to wealthy individuals out of an adult population of 7.6 million adults).  They equate allowing police to carry guns as the same thing as letting civilians defend themselves.  And they mistakenly rely on news reports to determine whether guns were banned in an area.  Unfortunately, the media virtually never mentions that attacks occur in gun-free zones.

In fact, since 2009 (indeed since at least 1950) only two of the mass public shootings have occurred in places where civilians were allowed to defend themselves with guns.  

Everytown asserts that attacks involving “assault weapons” were more deadly (7.7 with assault weapons versus 4.7 without).  Correcting their simple math errors, no longer counting stabbing deaths as shootings, and consistently defining “assault” rifles, cuts the difference to 6.4 versus 4.9.  Even then the difference is driven by just one attack.  For all the other mass shootings but Newtown, the lethality of attacks with “assault weapons” is actually slightly less than attacks without them.

With all the hundreds of millions of dollars that Michael Bloomberg is poring into pushing gun control, you would think that he could hire some fact-checkers.  But possibly he doesn’t care.  Maybe all he really wants is anti-gun propaganda.

John R. Lott, Jr. is a columnist for FoxNews.com. He is an economist and was formerly chief economist at the United States Sentencing Commission. Lott is also a leading expert on guns and op-eds on that issue are done in conjunction with the Crime Prevention Research Center. He is the author of eight books including "More Guns, Less Crime." His latest book is "Dumbing Down the Courts: How Politics Keeps the Smartest Judges Off the Bench" Bascom Hill Publishing Group (September 17, 2013). Follow him on Twitter@johnrlottjr.