(Reuters) - The conventional wisdom is that gun sales have increased dramatically since the election of Barack Obama because people fear gun rights will be curtailed. But as it turns out, there are no completely accurate measures of either gun purchases or gun ownership.
The gun industry's trade group, the National Shooting Sports Foundation (NSSF), tracks gun sales by looking at the number of new requests to the FBI's National Instant Criminal Background Check System (NICS). A check is required whenever someone buys a gun from a licensed dealer.
NSSF then adjusts the data, because one NICS request does not necessarily represent one new gun purchase. As Stephen Fischer, chief of multimedia productions at the FBI's Criminal Justice Information Services division, cautions: "An increase in the number of NICS transactions, for a given time period, should not be used to indicate an increase in the number of firearms sold."
He says several states run background checks each month on people with concealed-weapon permits. Thus some checks appearing in the NICS data don't mean that a firearm is being transferred, but simply that another check is being run on a permit holder. Also, he points out, a buyer may purchase more than one firearm in a single NICS transaction.
Based on adjusted FBI data, NSSF declared 2011 a record year for gun sales, with purchases in December topping 1.4 million. But NSSF general counsel Lawrence Keane admitted that this number is an estimate, and that his group does not try to guess how many guns are sold at gun shows without any background check.
"Most sales of firearms at guns shows are by licensed dealers," he said. "Something you never hear reported in the media."
Poll numbers about gun ownership are also imprecise. The NSSF cites an October 2011 Gallup poll that showed gun ownership was rising in the U.S. and that most Americans want less regulation on gun sales and ownership.
But gun safety advocates such as the Brady Campaign to Prevent Gun Violence counter with a regular survey on gun ownership conducted by the University of Chicago's National Opinion Research Center, which has been conducted 28 times since 1972, most recently in 2010. It has shown gun ownership declining steadily for years.
Pollsters have discovered, however, that these responses, too, are somewhat unreliable.
"You'd think that, for example, if you ask an adult in the home is there a gun in the home, that it wouldn't really matter if you spoke to the husband or the wife," said Philip Cook, an economics professor who studies guns at Duke University in Durham, North Carolina. "It turns out it matters a lot. Men are consistently more likely to say there's a gun in the home."
U.S. government statistics aren't precise either.
The U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) tracks the number of guns manufactured and exported by the U.S. each year. But NSSF's Keane said, "We find at times there will be companies missing from the data." ATF would not comment.
Finally, the Alcohol and Tobacco Tax and Trade Bureau, a division of the U.S. Treasury, tracks the total excise taxes paid on gun sales and imports by the private sector. (Military and law enforcement are excluded from the tax). Although that figure doesn't reveal the actual number of guns sold, it may be the best number available to describe the size of the industry. Total excise taxes were roughly $3.2 billion 2010, down from roughly $4.5 billion in 2009. The full figures aren't in for 2011, but the running tally for the first three quarters is roughly $2.9 billion.