Sunday, May 25, 2014

PolitiMath on uninsured Americans

An pseudonymous tipster pointed out problems with an old PolitiFact rating from 2009.

PolitiFact rated President Obama "Mostly True" for his statement that nearly 46 million Americans lack health insurance.

PolitiFact examined Census Bureau data confirming the president's figure, but noted it included 9.7 million non-citizens.  Our tipster pointed out that the number also included an estimated 14 million already eligible for government assistance in getting health insurance. 
The 2004 Census Current Population Survey (CPS) identified 44.7 million non-elderly uninsured in 2003. Blue Cross and Blue Shield Association contracted with the Actuarial Research Corporation (ARC) to provide a detailed analysis of the uninsured identified by the Census Bureau, which found:
  • Nearly one-third were reachable through public programs, such as Medicaid and the SCHIP program for children
  • One-fifth earn $50,000 or more annually and may be able to afford coverage
  • Almost half may have difficulty affording coverage because they earn less than $50,000 per year. Many of these people work for small firms that do not offer health coverage
Given that Obama was using the number of uninsured to promote the need for government intervention, PolitiFact should have mentioned the number of uninsured already able to take advantage of government help.  We're seeing that this year as at least 380,000 of those the administration says are gaining Medicaid through the ACA were already eligible before the law was passed. The administration can claim some credit for getting eligible persons signed up, but it's misleading to say all those signing up for Medicaid are gaining their coverage thanks to the ACA, just as it was misleading to use 14 million assistance-eligible Americans to show the need to offer more of the same kind of assistance.  The need was exaggerated, and PolitiFact failed to properly notice the size of the exaggeration.

The PolitiMath angle

We use the term PolitiMath of the relationships between PolitiFact's math equations and its "Truth-O-Meter" ratings.  Many journalists have trouble properly calculation error percentage, and in this item we find PolitiFact's former chief editor (Bill Adair) and its present chief editor (Angie Drobnic Holan) making a common mistake:
Getting back to Obama's statement, he said, "Nearly 46 million Americans don't have health insurance coverage today." That is the most recent number for the U.S. Census available, but he messes it up in one way that would tend to overcount the uninsured and in another way that would tend to undercount them.

It's an overcount because it counts noncitizens. Take out the 9.7 million noncitizens and the actual number is closer to 36 million. 

... So Obama is sloppy by saying it is for "Americans" but not accounting for the noncitizens, which leaves him off by about 22 percent.
PolitiFact's likely equation:  (46-36)/46   _21.7 percent_

It's the wrong equation, and this is not controversial.  It's basic math.  To find the percentage error the accurate value belongs in the denominator.

The right equation:  (46-36)/36    _27.7 percent_

Marc Caputo of the Miami Herald, a PolitiFact partner paper, made the same mistake months ago and vigorously defended it on Twitter.  Caputo argued that it's okay to do the equation either way.  One can execute the equation accurately in either form, but executing the wrong equation gives the wrong final figure.  Journalists need to consider the ramifications of having two different options for calculating an error percentage.  If one chooses the method in a way that favors one party over another then a pattern of that behavior turns into evidence of political bias.

Caputo used the method more damaging to the Republican to whom he referred.

In Adair and Holan's case, guess which party received the benefit of the wrong equation?

It's a statistic worth following.

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