Such studies include a 1998 study by economist John Lott, Jr. and a study by criminologists Gary Kleck and Marc Gertz. The argument by Lott and other proponents of permissive gun-carrying laws is that if more people could legally carry guns in public spaces, criminal predators would be deterred under the risk that would-be victims would be well-armed. The potential risk of these more permissive gun laws comes from the possible misuse of guns by those with concealed-carry permits and the potential complications that such laws may pose for police efforts to prevent illegal gun-carrying. Another cost is the possibility of an "arms race" between criminals and law-abiding citizens. Currently, some 75 percent of robbers do not use guns to commit their crimes. If more potential victims start carrying handguns, those robbers who continue to commit street muggings may be more likely to use guns to commit their crimes. They may be more nervous about the threat of the victim's having a gun and therefore be more likely to shoot first to pre-empt an armed victim response. Research by Philip Cook confirms that cities where more robbers use guns to commit their crimes also have higher robbery-murder rates. After examining the methodological flaws in Lott's study, this paper notes that the fundamental problem with Lott's research is the old social science adage "correlation is not causation," i.e., many variables may be related to one another yet not cause one another. Because of the many factors that are potential influences on the crime rate in a jurisdiction, it is difficult to control for all factors and single out one factor as the cause of a crime reduction when comparing crime rates across jurisdictions. Kleck and Gertz, in their analysis of the defensive uses of guns, claim that there are 2.5 million defensive guns uses per year, based on a telephone survey of 5,000 American adults conducted in 1992. Possible sources of error in telephone surveys, particularly ones that solicit information on actions that have been taken by respondents, are fraught with error risks. Corroborative evidence is crucial in such cases, and such evidence was not forthcoming in the Kleck and Gertz study. Although research by John Lott and Gary Kleck has challenged the prevailing view that gun regulations can reduce lethal crimes, the many limitations of Lott's and Kleck's research indicate that there is no reason to move from the relationship between guns and violence backed by research in previous decades. Until proven otherwise, the best science indicates that more guns will lead to more deaths. 19 notes