DETROIT, MI — Would a Medicaid expansion in Pennsylvania cost the state millions? Billions? Or will it actually bring in a surplus of revenue, while simultaneously providing health coverage for more citizens? All these possibilities—and more—have been presented in the state’s media coverage. And while the range of numbers reflects real political and analytical disagreement among different sources, Keystone State reporters can do more to press officials for the source of their figures and help readers sort through a genuinely confusing picture.

As background: the national healthcare reform law calls for the expansion of state Medicaid programs, and provides for the federal government to bear most of the cost of that expansion—100 percent for the first three years, stepping down to 90 percent in 2022 and beyond. But the Supreme Court ruled that states must be allowed to choose whether to accept the expansion, and in early February, Gov. Tom Corbett, a Republican, signaled that Pennsylvania would reject the deal.

“Our initial estimates show that a Medicaid expansion … would cost Pennsylvania almost $1 billion of new state taxpayer dollars through fiscal year 2015-2016 — ultimately rising to a total cost of more than $4.1 billion of new state taxpayer dollars by the end of fiscal year 2020-2021,” Corbett wrote to Health and Human Services Secretary Kathleen Sebelius. (At the same time, Corbett has left the door open to negotiation. There is no deadline for states to agree to the expansion, though the longer they wait the fewer federal dollars they qualify for.)

The governor’s $4 billion estimate got picked up in early coverage, like this piece from the Pittsburgh Post-Gazette. But Corbett’s letter offers no data to support the cost estimate, and none has been forthcoming since—even as, as the Allentown Morning Call and The Philadelphia Inquirer report, Democrats challenged the governor’s budget secretary for data to back-up the figure at budget hearings that began this week.

Meanwhile, other economic projections are proliferating. A Feb. 21 post by David Wenner at PennLive, the website of The Patriot-News in Harrisburg and other central Pennsylvania papers, cites (and, gratifyingly, links to) a study from Families USA and the Pennsylvania Health Access Network that predicts federal funds tied to the expansion would lead to more than $5 billion in economic activity in the state in 2016, helping support more than 40,000 jobs.

And a report from the Pennsylvania Health Law Project and the Office of Rural Health at Penn State forecasts that expansion would actually save the state hundreds of millions in the first three years, while generating more than $50 million in new tax revenue. That analysis was written up by reporter John Finnerty for smaller outlets like New Castle News and The Tribune-Democrat, though it appears, alas, always without a link.

With so many numbers floating around, it’s hard to get a handle on what, exactly, is a substantive contribution to the policy debate, what is just political exaggeration, and what the numbers—if they are to be believed—really mean. How can reporters sift through all this, put pressure on public figures to use credible data, and give Pennsylvanians a sense of what they can trust?

Part of the trouble is that the cost-benefit estimates typically come from either partisan elected officials or advocacy groups, who have motives to cherry-pick figures to support predetermined positions—and who may or many not be forthcoming about how they made their calculations. The terms of the debate also get shifted, between the narrow effect of Medicaid on the budget and broader economic impact, in sometimes slippery ways.

In that context, credible projections from independent sources are a crucial resource for journalists. So it’s a little surprising that another report, released in November by the Urban Institute and the Kaiser Family Foundation, hasn’t gotten more coverage. That nonpartisan analysis examined the budgetary consequences of expansion in every state in the nation. It forecast that, by 2022, Medicaid expansion would provide 542,000 Pennsylvanians with health care they didn’t have before, and that expansion would cost the state $2.8 billion—not $4.1 billion, as Corbett claims—while the federal government would pay $37.8 billion.

Anna Clark is CJR's correspondent for Michigan, Wisconsin, Ohio, and Pennsylvania. A 2011 Fulbright fellow, Clark has written for The Guardian, Grantland, and Salon; blogs at Isak; and can be found on Twitter @annaleighclark. She lives in Detroit.