Minnesota is due to issue its December 2008 job loss figures later today, thus closing the book on a wretched year for state employment.

As for 2009, Minnesota Department of Employment and Economic Development (DEED) research director Steve Hine tells me that current (unofficial) projections by Global Insight, the consulting firm retained by the state, point to roughly 61,000 more lost jobs.

How does that compare to 2008? We’ll have a better idea when the December figures come out–the estimate Hine gave legislators last week was 39,000–but not necessarily an authoritative one. The growth in the ranks of the unemployed depends on the data you’re using.

A case in point: According to figures published by DEED, Minnesota’s economy shed 30,800 jobs between November 2007 and November 2008. That seems straightforward enough. It means around 31,000 more Minnesotans were unemployed in November ’08 than in November ’07, right?

No. According to the federal Bureau of Labor Statistics, the number of unemployed Minnesotans grew by 57,053 during the same time frame–almost twice as many as the DEED figure would suggest to the average reader.

That’s not a minor discrepancy. I called to ask Hine about the difference. “These are different surveys of different measures,” he says. “The [DEED] jobs number is based on a payroll survey. The BLS unemployment numbers come from a household survey.” Some of the differences: The self-employed (a category that includes independent contractors and freelancers) aren’t counted in payroll surveys. Neither are new entrants, or re-entrants, to the job market. Hine adds that sampling error could be a factor as well.

For comparison’s sake, the 61,000 jobs lost projection for 2009 is a payroll survey estimate; it correlates to the current figure (still an estimate at this point) of 39,000 for ’08. In other words, the expectation is that the growth in state unemployment in 2009 could be 50 percent higher than in 2008.

Hine warns that those ’09 projections are very much in flux, however. “Right now,” he offers, “it’s very back-of-the-envelope calculations. The very rough estimate is that if we were to lose jobs next year at the forecasted Global Insight rate, we would lose about 61,000 jobs this year. These GI forecasts have changed drastically month to month. They’re a moving target. We do projections every three months, and the next set will be coming out in a couple of weeks.”