Charlotte-Mecklenburg Schools has relied far more heavily on mass teacher layoffs to deal with three years of budget tightening than other N.C. districts, according to a school layoff tally issued by the state this week.

CMS, which has about 9 percent of the state's students, accounted for roughly 40 percent of all teacher layoffs from 2008-09 to 2011-12 - and for 70 percent of last year's.

But more than anything, the report designed to clarify the connection between budget cuts and education jobs illustrates just how difficult that is.

For instance, the stark contrast between the state's two largest districts - CMS reported 883 teacher layoffs and Wake County none - comes partly from officials interpreting the question differently. CMS counted as layoffs hundreds of teachers whose short-term contracts were not renewed; Wake did not.

The report produces "more questions than answers," said Chris Haynes, a policy analyst for House Speaker Thom Tillis.

Tillis, R-Mecklenburg, said he's pushing for the state to compile reliable information on jobs lost and gained in every school district to help prevent conflicting claims.

"I want to cut through all that rhetoric," he said Thursday, but called the state survey of school districts "rather unsophisticated."

The report provides a snapshot of four painful years - and forecasts another tough one coming.

All told, N.C. public schools laid off about 2,200 teachers, 2,500 assistants and 1,470 other employees from 2008-09 to 2011-12, the N.C. Department of Public Instruction reported.

In addition, almost 10,600 vacant jobs in K-12 education were abolished, for a total cut of about 8 percent of the workforce that started the year in 2008, officials said.

"This is the first time since the Great Depression in the 1930s that North Carolina public schools have decreased the number of teacher positions during a time of student growth," the report says.

More than 4,000 public school employees, including 480 in CMS, are being paid with federal "EduJobs" money that ends next year. That means the battle over how much taxpayers should spend to save teachers is bound to flare again in 2012.

The report won't settle the toughest questions about education spending and jobs.

As anyone trying to sort out school spending discovers, it's complicated. Districts spend a mix of state, county and federal money. Changes in any one of those can slash or add jobs. Schools also gain teachers when enrollment rises and lose them when it slumps.

CMS, for instance, entered the recession with a relatively generous budget from Mecklenburg County, which paid for hundreds of teachers.

When the county cut spending in 2009, CMS started layoffs before most other districts. Now, with an infusion of county dollars and the federal jobs money, CMS is adding 500 teachers while districts such as Cumberland, Gaston and Burke are laying off dozens.

While the DPI news release described the job cuts as "in response to state budget cuts," the survey of school districts asked for all cuts, regardless of the source. And it did not ask about jobs added. As budgets shift, districts often eliminate some jobs while creating others.

The job survey found almost 16,700 jobs eliminated, or 8 percent of the 2008-09 workforce. But a separate tally of total employment shows the drop at about half that size - about 8,200 employees, or 4 percent.

Likewise, CMS reported eliminating more than 2,500 jobs from 2008-09 to 2011-12, including layoffs and vacancies. But payrolls provided to the Observer in March 2008 and April 2011 show a decrease of 1,126 employees.

Another challenge: When you ask for data from 115 school districts, there are bound to be problems.

When CMS first submitted its data, state staff suspected it was wrong. CMS sent a corrected version - which the state forgot to enter before publishing the report on Wednesday.

When reporters raised questions, DPI retracted the report, then reissued a corrected version late Wednesday.

But CMS numbers still appear contradictory. The state asked for all jobs eliminated, whether vacant or filled, then asked how many of those required a layoff.

CMS reported eliminating 252.5 teacher jobs in 2009-10 but laying off 570 teachers.

Spokeswoman LaTarzja Henry said Friday that's because when teachers leave during the school year, CMS hires replacements on short-term contracts that expire at year's end.

Because those people lose their jobs, CMS tallied them as layoffs, even if the position is going to be filled. Some individuals were laid off in 2009-10, rehired and laid off again in 2010-11.

Wake County eliminated jobs filled by people on year-end contracts but did not count them as layoffs because those people did not have an ongoing contract, said Wake spokesman Greg Thomas.

Meanwhile, Guilford County, the state's third-largest district, did not submit information.

When contacted by the Observer, Chief of Staff Nora Carr said Guilford got the request but mistakenly believed it was a duplicate of a job survey sent by another group.

Guilford had submitted its numbers to DPI on Friday, but state officials said it will likely be Monday before that gets posted.