We talked Thursday about a controversial McKinsey & Company report, which generated quite a stir this week with a survey about the Affordable Care Act. According to the study, nearly a third of American businesses will stop offering health coverage to their employees as a result of the new reform law. Several news outlets pounced on the release of the report, as did many Republicans.

The findings were sharply at odds with all available evidence, leading reporters to want to examine the report’s methodology. McKinsey & Company refused requests for additional information, shielding the study from scrutiny, which further raised suspicions about its validity.

Greg Sargent reports that White House aides, as well as leading Democratic officials in the House and Senate, have also reached out to McKinsey with questions about the survey’s methodology — if the report is accurate, it stands to reason officials need to know more about this — and again the consulting firm refused all requests.

Brian Beutler takes this story a little further still, noting that even within McKinsey & Company, there are officials unhappy with how their own firm has conducted itself.

[M]ultiple sources both within and outside the firm tell TPM the survey was not conducted using McKinsey’s typical, meticulous methodology. Indeed, the article the firm published was not intended to give the subject matter the same authoritative treatment as more thorough studies on the same topic — particularly those conducted by numerous think tanks, and the Congressional Budget Office, which came to the opposite conclusion. And that’s created a clamor within the firm at high levels to set the record straight.

“This particular survey wasn’t designed in a way that would allow it to be peer review published or cited academically,” said one source familiar with the controversy. […]

Another keyed-in source says McKinsey is unlikely to release the survey materials because “it would be damaging to them.”

Both sources disagree with the results of the survey, which was devised by consultants without particular expertise in this area, not by the firm’s health experts.

McKinsey has to realize it has a lot of explaining to do. This is the sort of controversy that can do lasting damage to a firm’s credibility.

Indeed, the questions are piling up. How was the survey conducted? What were the questions? Who wrote them? Why did McKinsey abandon its usual methodology for this one project? When McKinsey “educated” survey participants, what language was used that might have affected the results? And who paid for all of this?

As Paul Krugman added yesterday, “[I]f you ask me, this is a lot more important than some sex scandal.”

In the meantime, any Republicans citing this McKinsey report as evidence of the ACA’s flaws are obviously not to be taken seriously.

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Follow Steve on Twitter @stevebenen. Steve Benen is a producer at MSNBC's The Rachel Maddow Show. He was the principal contributor to the Washington Monthly's Political Animal blog from August 2008 until January 2012.