Unlike a medical convention or a trade show, most SMERF attendees pay their own way.

And most are on tight budgets.

• In estimating what convention attendees spend, the CRVA has routinely made erroneous claims, sometimes contradicting itself.

When Charlotte landed the 2010 National Rifle Association convention – one of the city’s biggest-ever meetings – the CRVA estimated gun enthusiasts would spend $10.3 million.

After the NRA left, the CRVA inexplicably increased that total by 600 percent – adding tens of millions of dollars of spending that was trumpeted to the public.

In other events, the CRVA said some conventions were attended by thousands more people than actually showed. For the recent Shriners convention, the tourism authority overestimated attendance by 40,000 people.

In interviews with the Observer earlier this year, the CRVA’s research department adamantly defended its spending formulas.

Recently, however, the CRVA acknowledged that many of its past spending estimates were erroneous. It is now using a new formula that more realistically reflects visitor spending – and has cut most estimates in half.

“We owe it to the community to be as accurate and as conservative as possible,” said Kimberly Meesters, who became CRVA spokesperson this spring as part of a reorganization by new chief executive Tom Murray. “We plan to take a much more disciplined approach in the future.”

The CRVA, which manages the center, and the city, which owns the building, argue that the center’s economic benefits remain crucial for the growth of Charlotte.

Murray acknowledges that the Convention Center loses money, which is the case in many cities.

“Not all businesses are designed to make a profit,” Murray said. “The real mission is to create economic impact.”

He says he believes it’s a moneymaker for the city. The convention business pays off, he said, in jobs and new tax revenue for the city.

“The wonderful secret is that for every $1 in tourism tax … (it yields) $1.10 in general fund tax,” Murray said.

That’s only true, however, if roughly $25 million of Convention Center expenses are ignored, including nearly $22 million in annual debt payments.

In fact, there is no evidence that the city makes its Convention Center money back in new taxes from visitor spending. The city of Charlotte, Mecklenburg County and the state may make as little as 35 cents for every dollar they spend on the convention business. Convention origins

Cities across the country, including Charlotte, believe convention centers are must-haves, like stadiums or museums. They argue that conventions give their cities nationwide exposure, making it easier to attract businesses.

One of Charlotte’s earliest forays into the convention center business came at the turn of the last century.

A group of eight businessmen built a privately financed civic auditorium at Fifth and College streets and a hotel where the Marriott Center City is now.

But there was a problem: The building lost money, and the original investors were soon in bankruptcy court. The city ultimately bought the building in 1911 and jumped into the convention center business.

Fast forward to the late 1980s, when business leaders, including Hugh McColl, lobbied to build a new publicly financed convention center to replace the old city-owned center at the site of what is now the EpiCentre entertainment complex.