RALEIGH – As the General Assembly continues to fashion the state’s 2010-11 budget, spending lobbies are employing all the usual tactics to defend their jobs, incomes, grants, and contracts. These tactics include public statements, private meetings, press releases, email blasts, and statistical malpractice.

I thought I might get your attention with that last phrase. When budgets get tight, people start playing loose and fast with the basic facts of public finance. Costs become benefits. Small-than-expected increases become cuts. In my experience, the worst offenses occur right after someone utters the magic phrase “multiplier effect.”

There’s no question that the purchase of a good or service has secondary effects on private incomes. Every hamburger you buy puts money into the pockets not just of the employees of the fast-food joint you frequent but also the producers of the food, the manufacturers of the packaging, the store’s other vendors, and all the individuals with whom these initial beneficiaries subsequently do business.

Politicians and spending lobbies who make multiplier-effect arguments about the economic benefits of state spending seem to think that governments have some special ability to generate ripples of economic activity. For some reason, it never seems to occur to them that any dollar spent on any good or service must, by definition, have multiplier effects.

Every time a dollar is collected in taxes and then expended on a government program, there are two sets of multiplier effects. There’s the ripple effect from the government expenditure of that dollar and the ripple effect from the lost expenditure of that dollar by the person who originally earned it.

So to argue a net benefit from a governmental expenditure, you have to show that the total value of goods and services stemming from it exceeds the total value of the goods and services lost because of it. I’m not an anarchist, so I freely admit that there are cases in which government expenditure has a net positive effect.

But not many.

In political debates about government budgets, those who most often resort to multiplier-effect arguments are usually those who have the shakiest grasp of them. For example, as I have written about in the past, advocates of government arts subsidies tend to retreat to economic-benefit claims because it is exceedingly difficult to make a straightforward case for taxing middle-income North Carolinians to subsidize the aesthetic and entertainment preferences of the disproportionately affluent North Carolinians who enjoy the symphony, the ballet, the opera, and the gallery (I’m in the latter group, by the way, but I’d prefer to pay my own bills if you don’t mind).

Patronage of North Carolina’s system of state parks isn’t so wildly skewed towards the wealthy. For generations, many state residents and visitors of all backgrounds have enjoyed fishing the state’s waterways, hiking the state’s mountain trails, watching the state’s wildlife, and exploring the state’s natural beauty. Still, rather than sticking to the tried-and-true case for partial taxpayer subsidy of parks – Milton Friedman famously constructed a creative, if not wholly persuasive, case – North Carolina’s park lobbyists have resorted to concocting their own multiplier-effect magic.

It worked about as well as my son Andrew’s clumsy card tricks – when he was about four.

In a Raleigh News & Observer story on fiscal challenges to the state’s parks, system director Lewis Ledford characterized a 2008 study by N.C. State University researchers as demonstrating that state taxpayers get “a good return on the investment” of tens of millions of dollars every year because non-local visitors spend an average of $23.56 on gas, meals, and other services while visiting state parks.

I found the original study on the park system website. Ledford correctly cited the statistic but seems not to have understood its import. The definition of “non-local visitor” was based on county lines, not state lines. Someone who traveled to Eno River State Park from, say, Dunn or Asheboro was counted as a non-local visitor. But that person is obviously a North Carolinian. You can’t consider his spending to have been attracted to North Carolina by the park.

In other words, the study in question says precisely nothing about whether North Carolina taxpayers derive net economic benefits from being forced to subsidize parks. The analysis does suggest that North Carolina communities containing or abutting state parks tend to gain income from communities that don’t contain or abut state parks. Big surprise.

Given that the vast majority of state park users are from North Carolina, it is highly unlikely that a valid application of economic-impact modeling would show a significant net benefit to state taxpayers.

If you believe in subsidizing parks for some other reason, make your case. But let’s cut out the statistical malpractice.

Hood is president of the John Locke Foundation.