HERE'S A TIP: When politicians refer to jobs numbers, be wary and forearmed.

There are too many ways to present such numbers in ways that dupe the public.

Worse, the feds provide so many sets of numbers that it's easy for pols to play tricks.

Gov. Corbett's first re-election campaign ad says he put Pennsylvanians back to work with "a remarkable 116,000 new private-sector jobs."

In May, the governor put his new jobs number at an "outstanding" 125,000.

The state Department of Labor & Industry said it was 125,700.

And Democrats say the state lost jobs.

The problem? Nobody - not the governor, his campaign, his administration nor the Democrats - is telling the whole story.

For the whole story, you need to know that job numbers change every month; not all job numbers are the same; and every state gained jobs since Corbett took office - many far more than Pennsylvania.

I'll get back to this, but first a short tutorial.

The Bureau of Labor Statistics in the U.S. Department of Labor releases data each month on state unemployment rates and jobs.

It's collected two ways: a survey of employers called the "establishment" survey and a survey of employees called the "household" survey.

The former is conducted by the statistics bureau, the latter by the U.S. Census Bureau.

For pols, this double-counting gives everybody something to crow about because there's often a big difference in results.

Why? Employers report only payroll. Households also report the self-employed and, according to experts, offer a less-reliable measurement.

So when numbers came out last month, the state Republican Party praised Corbett for adding 24,000 jobs; the state Democratic Party issued a statement saying the state lost 9,200 jobs.

Both numbers are correct.

The employer survey said we lost jobs; the household survey said we gained jobs. Statistics bureau officials say that happens, that the two numbers tell different stories and that's just how it is.

Oh, the estimated 9,200 jobs lost? The feds say that in a state such as ours, with nearly 6 million jobs, it is not statistically significant.

Confusing, no?

"It is," says Peter Cappelli, a business-management prof and director of the Wharton School's Center for Human Resources, "but it's a big country and we're really not all that great in figuring out what's going on."

He says there's "some value" in the two surveys to watch for changes, but he and others caution against judging a state on the basis of one month, whether by job counts or unemployment rates.

He says the best measure is net new jobs over time.

When one looks at net jobs here since January 2011, the picture is less than "remarkable."

The current net jobs gain is not 116,000. It's 75,100.

Among the 10 largest states, of which we're sixth, we gained the fewest jobs.

If you're thinking, well, those five larger states have more people so having more jobs makes sense, that's true.

But data on the four states with less population (Ohio, Georgia, Michigan and North Carolina) show each gained double the number of jobs we did, or more.

Smaller states. Double or more job gains.

New Jersey gained more as well; as did Maryland. So neighbors Ohio, New York, Maryland and Jersey all gained more jobs than us since Corbett took office.

The statistics bureau tracks this every month. The next state-by-state numbers are due July 19.

So what's the deal with Corbett's 116,000?

That's only private-sector jobs. Not counting public jobs.

This in a state with 500 school districts and 2,500-plus municipalities where tens of thousands of teachers, firefighters, cops and other government workers lost jobs that feed the economy and tax bases like any other job.

Why doesn't Corbett count those? I mean, other than the obvious fact that the number isn't so "remarkable"?

"The key point is the private sector," says Corbett campaign manager Mike Barley. "The governor said he was going to work for government efficiency . . . many would argue government gets in the way [of job creation] . . . so the private sector is what we're highlighting."

Which is fine, as long as you know who's counted, who's not, who's doing the counting and why.

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