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Lawmakers in over 30 states have enacted permissive concealed-carry gun laws, which make it legal for citizens to carry concealed handguns. These laws will have a significant impact on both crime and public health. Proponents of these laws assert that citizens carrying concealed guns will deter criminals from committing crime. While opponents argue, the more individuals carrying concealed handguns the increase in the likelihood that someone will be injured or killed.

John R. Lott Jr., a John M. Olin Visiting Law and Economics Fellow at the University of Chicago, has campaigned for the enactment of permissive concealed-carry laws and is at the center of the debate. Pro-gun activists have seized upon his research to advocate for more permissive concealed-carry gun laws. He summarizes his findings in his controversial book, More Guns, Less Crime. Using data from the FBI Uniform Crime Reports, he reports the effects of concealed-carry gun laws on various types of crimes in all 3,054 counties in the United States from 1977 to 1992 and makes the following questionable claims:  


1. Lott's study suffers from numerous methodological problems, which bias his results.  

Lott does not properly control for factors, such as poverty, the illicit drug market, gang activity, which can affect crime. Lott uses methodology that was discredited over two decades ago by the National Academy of Sciences.

2. Lott does not prove that "more guns" cause "less crime", as implied by the title of his book. In fact, he provides no credible mechanism to describe this alleged phenomenon.

Were there more guns? Most surveys show either a decrease or no change in gun ownership. Since there aren't "more guns", Lott's entire argument is invalid. To find that the enactment of concealed-carry laws actually reduce crime, Lott assumes the following series of events:

"Shall-issue" law passes --> Increase number of permits issued --> Increase handgun carrying by citizens --> Increase use of handguns for self-defense against crime --> Criminal alter their behavior --> Change in rate and pattern of crime".

However, Lott investigates only the first and last steps in the process, providing little empirical evidence that any of the necessary intermediate steps occur as described above. Since many of these intermediate steps do not occur, as Lott assumes, Lott's conclusions fall short and can not be valid.

3. Lott avoids many implausible conclusions that can be obtained from his work.

According to Lott's data, middle-aged and elderly black women (as victims or perpetrators) have a greater effect on reducing the murder rate than young black males. Lott would have us believe that if law enforcement focused on the activities of middle-aged or elderly black women, we could dramatically reduce crime. Lott's data show that an increase in unemployment or a decrease in income level reduces crime. The data imply that we could reduce crime by firing people from their jobs. 

4. Lott's own data contradicts or is otherwise inconsistent with what he claims.

For example, Lott claims that "blacks benefit more than other groups from concealed-handgun laws". Yet, data, on page 99 (Table 5.2) of his book, show that the percentage of black victims actually increases if concealed-carry laws are enacted. 

5. Sometimes Lott is just plain wrong.

Lott claims that there were only 200 accidental handgun deaths in the U.S. in 1988. Unfortunately, his estimate is off by more than a factor of three. This invalidates his entire analysis on concealed-carry laws and accidental shootings.

6. Lott's conclusions are not consistent with well-established criminological theories.

Concealed-carry laws should exert the greatest effect on criminal activity in public. Since robberies usually occur during interaction with strangers, one would expect to find a large decrease in robbery due to concealed-carry laws. Yet, according to the data in his study, concealed-carry laws have little or no effect on robbery. On the other hand, Lott reports that concealed-carry laws have the greatest effect on murder, rape and aggravated assault, presumably in public. However, one should find this strange because murder, rape and aggravated assault usually are committed in private (i.e., the home) by persons known by the victim.

7. Lott erroneously finds that a criminal will substitute violent crime for property crime, when deterred by a gun.

Simply put, why would a murderer or rapist want to steal a car or burglarize someone's home, if he felt deterred by a gun? Neither common sense nor valid theories in criminology supports Lott's supposition.

8. Lott falsely claims that concealed-carry laws can prevent mass public shootings.

In another study, using newspaper articles as his main source of data, Lott reports a rather large reduction in death and injury from mass shootings when concealed-carry laws are enacted. This claim is invalid for three reasons. First, newspapers are a biased source because they tend to underreport the number of assaults, rapes, suicides and firearm-related events and report some types of homicides (presumably, more "newsworthy") more than others. Second, without concealed-carry laws, states, such as Oklahoma, Kansas, Alaska and Louisiana, which have a ban on concealed weapons, would have experienced a drop in mass murders anyway. Third, Lott uses the same faulty methodology in this study on mass shootings as in his other study.

9. Lott tries to address many criticisms of his work unsuccessfully using misleading statistical methods and graphs. 

Despite claims to the contrary, Lott's statistical methods do not control for many of the methodological flaws outlined above. For instance, he uses unemployment insurance payments as a proxy for poverty, but this may be inappropriate because some states may be more generous with the unemployed than others.

Lott's graphs, which form the basis of many of his arguments against his critics, are flawed. Most of the crime rates used in his graphs do not match the rates published in the FBI Uniform Crime Reports. Also, Daniel Webster, a Johns Hopkins University professor, notes that the "shall-issue" states, which Lott uses in his graphs, are not the same each year.

10. At least ten different academics from the Johns Hopkins School of Public Health, Harvard School of Public Health, University of Chicago, Carnegie Mellon, Georgetown, Emory, and Northwestern University, have called Lott's work into question.

Researchers provide ample evidence that Lott's work is flawed. For instance, Jens Ludwig, a professor at Georgetown University, provides the most definitive proof of this. He did a study comparing youth homicide and adult homicide in order to control for all the factors not accounted for in Lott's study. Because youths can not obtain concealed-carry permits, youth homicide should remain unchanged, as compared to adult homicides, which, according to Lott, should decline, if concealed-carry laws were enacted. However, Ludwig discovered, if anything, that there is an increase in homicide from concealed-carry laws. In addition, Black and Nagin from Carnegie Mellon University, as well as others, have reanalyzed Lott's data and found that concealed-carry laws have no consistent effect on violent crime.

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