Yet as Lott's profile rose, his work came under scrutiny. The National Research Council, a branch of the National Academy of Sciences, assembled a panel to look into the impact of concealed-carry laws; 15 of 16 panel members concluded that the existing research, including Lott's, provided "no credible evidence" that right-to-carry laws had any effect on violent crime. Economists Ian Ayres of Yale University and John Donohue of Stanford University argued that Lott had drawn inaccurate correlations: Cities had experienced a spike in crime in the 80's and 90's in part because of the crack epidemic, not because of strict gun laws. When they extended their survey by five years, they found that more guns were linked to more crime, with right-to-carry states showing an eight percent increase in aggravated assault.
Kleck reexamined Lott's work and found that he hadn't accounted for missing data. "It was garbage in and garbage out," he says. Even Kleck, who conducted a controversial, yet often-cited survey on defensive gun use, observes, "Do I know anybody who specifically believes with more guns there are less crimes and they're a credible criminologist? No." David Hemenway, the director of the Harvard Injury Control Research Center, has concluded that "virtually all of Lott's analyses are faulty; his findings are not 'facts' but are erroneous." Lott maintains that the missing data Kleck refers to had no impact on his final conclusions, and that the "vast majority" of economists and criminologists support his findings.
Researchers pressed Lott, then a resident scholar at the American Enterprise Institute, to release the data behind his claim that 98 percent of defensive gun uses in the United States involved a would-be victim merely brandishing a gun. Lott claimed that it was based on a data from a survey he had conducted—but that the data had been lost in a computer crash. Lott redid the survey in 2002; of more than 1,000 people surveyed, seven said they'd used a gun to defend themselves. Of those seven, six merely flashed a firearm in self-defense. Based on these responses, plus the lost data, Lott still asserts that more than 90 percent of defensive gun uses involve brandishing a gun.
As criticism of Lott mounted, an online commenter, who identified herself as a former student of Lott's at Penn named Mary Rosh, lavishly praised her former professor and attacked his critics. "He was the best professor that I ever had," she wrote. After it came out in 2003 that Rosh and Lott shared an internet address, Lott admitted to the sock puppetry, saying that he had been receiving obnoxious phone calls when using his real name, and some of Rosh's comments were possibly written by his family members on a shared email account. "In most circles, this goes down as fraud," wrote Science editor-in-chief Donald Kennedy in the magazine. And yet, he observed in a blistering op-ed, "Legislators in a number of states are still considering liberalizing concealed-weapon laws, and Lott's book plays a continuing role in the debate. That moves this story from high comedy to a troubling challenge in social policy that isn't funny at all."
http://www.motherjones.com/politics/2015/07/john-lott-guns-crime-data