When the number of people carrying concealed handguns increases, crime decreases.

That’s the socially controversial finding of Binghamton University economist Florenz Plassmann and his collaborator, who used the principles of supply and demand to analyze crime rates.

Plassmann’s premise was detailed in an article in the October 2001 issue of Journal of Law and Economics. The article, “Does the Right to Carry Concealed Handguns Deter Countable Crime? Only a Count Analysis Can Say,” was written by Plassmann and T. Nicolaus Tideman, who was Plassmann’s dissertation adviser at Virginia Tech.

Plassmann’s assertion isn’t the first of its ilk, but it is something of a surprise to him, he admits.  In a 1997 book More Guns, Less Crime, economist John Lott similarly analyzed the relationship between the right to carry concealed handguns and the crime rate. Lott was the first to use economic principles to suggest that concealed weapons have a clear deterrent effect. If more people carry concealed handguns, crime decreases, his study showed.

Plassmann, an assistant professor of economics, says he was certain that a re-examination of Lott’s work would find Lott’s methodology questionable and his conclusions mistaken, he said.

“I believed guns would increase crime,” he said. “I had just finished a dissertation analyzing data similar to Lott’s. His data are ‘count data’ (non-negative integers), which means that you cannot have a negative number of murders, or 2.5 robberies. If you analyze such data with standard methods, you are likely to get erroneous estimates. Because Lott had ignored this, I thought that I had a valid reason not to trust his results.”

When Plassmann contacted Lott about his concerns, Lott turned his data over to Plassmann and encouraged him to re-examine the methodology and attempt to replicate the results.

“I did my own analysis,” Plassmann said. “To my surprise, it suggests that the right to carry concealed handguns does deter crime. Lott’s analysis has been criticized because his findings are not very stable, but our results are much more robust.

“To emphasize that a statistical analysis is valid only if the statistical model fits the data, we included a little play on words in the title of our article: Because crimes are ‘countable,’ you must examine them with a ‘count’ analysis, and not with standard methods,” he added.

Plassmann and Lott are now working together on related research. They are writing a paper that examines the relationship between gun ownership and crime.

The concept of viewing crime through an economic lens actually stems from the work of Gary Becker, a Nobel Prize-winning economist, Plassmann said.

“We can see crime as the outcome of supply and demand,” he noted. “If all potential victims are unarmed, crime is easy and, therefore, inexpensive. However, if potential victims are armed, crime becomes more difficult and expensive.”

From the “demand” perspective, when the cost of preventing crime becomes more expensive then the “demand” to commit it, the more likely society is to let another crime happen, Plassmann said.

As a researcher, Plassmann doesn’t advocate for or argue against carrying handguns, concealed or otherwise.

“I think all this analysis can do is suggest that the theory ‘More guns will cause more crime’ is probably not correct in this simple form,” he said.