In an age when so much research is so obviously driven by a sponsor's agenda, yet those sponsors deny with indignance that they had any influence over numbers that bolster their policy goals, it was refreshing last week to see a researcher and advocacy group admit that biases shaped their "study."

On Saturday, the Progressive Leadership Alliance of Nevada released a report which found that Hispanic immigrants bring an overall economic benefit to Nevada. The report, compiled by Chicago-based researcher Robert Ginsburg of the Center on Work and Community Development, limited its analysis to Hispanic immigrants' overall share of the work force and how much they pay in taxes. According to their report, Hispanic immigrants comprise 18 percent of Clark County's work force and paid $1.6 billion in state and local taxes in Nevada in 2005.

Conveniently, the report does not address how much governments spend to provide illegal immigrants with public education and welfare benefits, and whether these immigrants place a disproportionate burden on law enforcement and corrections systems.

These issues have driven voters in a number of states, including neighboring California and Arizona, to approve ballot questions that expressly limit illegal immigrants' access to public services.

But addressing these costs would have damaged the purpose of the "study": to spin illegal immigration as a bed of roses, sans thorns.

At least those behind the project acknowledged as much.

"What we tried to do is make the point that Nevada needs immigrants," Mr. Ginsburg told the Review-Journal.

"We want to reframe the way that Nevadans view immigration and immigrants," said Bob Fulkerson, PLAN's state director. "We want to help people understand the huge contributions immigrants make to Nevada and understand that immigration is vitally important to the state."

And the best way to "reframe" the immigration debate is to drop the word "illegal" from the discussion and ignore the pressure illegals place on government budgets.

There's a big difference between legal and illegal immigration. A small share of immigrants wait for the opportunity to lawfully enter the country, learn its history and its language and become citizens. Millions more simply dash across our borders, find work, collect a paycheck and wire some funds back home, never fully assimilating this nation's values, never fully appreciating its freedoms.

One group is in the country legally, the other criminally.

Not only does PLAN's report lump legal and illegal immigrants into one labor pool, it disregards immigrants of other races and ethnicities. To be sure, the vast majority of legal and illegal immigrants in Nevada are Hispanic, but the report insinuates through omission that African, Asian and European immigrants are of no benefit to the state.

In fact, many thousands of local workers from the Philippines, the Balkans and Africa are making positive -- and legal -- contributions to Clark County's economy every day.

This "study" is nothing more than an attempt to rehabilitate the political image of illegal Hispanics, who only a year ago marched through American cities waving Mexican flags and signs written in Spanish, causing widespread public outrage and huge liabilities for elected officials sypathetic to their demands for amnesty.

Yes, Nevada's economy clearly requires a supply of immigrant labor. But any examination of its costs and benefits to the state must begin with an estimate of how many immigrants are here illegally -- and end with how they affect our overall tax burden.