The FTC study, eight years in the making, also tracked consumers as they tried to fix or dispute errors in their credit reports. More than one in 10 who did this saw their credit score change as a result.The study was ordered by Congress in 2003, when it passed the Fair and Accurate Credit Transaction Act. The FTC followed 1,001 consumers as they tried to navigate the credit report system and to fix mistakes in their reports.

Among other things, the study found:

26 percent of consumers in the study identified a "potentially material error";



21 percent managed to obtain a modification of an error;



Roughly half of that group experienced a change in credit score;



Most of those credit score changes were minor, with roughly half resulting in swings of 20 points or less;



The most important finding of all: For 52 of individuals studied, "the resulting increase was such that their credit risk tier decreased," meaning they were likely to get cheaper loan rates.



Consumer groups responding to the study said it indicates a need for reform of the credit reporting industry."It's unconscionable that 40 million American have errors in their credit reports, and that 10 million have errors grave enough to cause them to be denied or charged more for credit or insurance or even be denied a job," said Chi Chi Wu, staff attorney at the National Consumer Law Center.

Studies of credit report errors have been conducted before, but they have produced confusing results. Many errors are not material — a misspelled street name for example. And errors are not the real problem — lower credit scores that cost consumers when they try to get loans are. Credit bureaus are required by law to quickly fix mistakes, but there have long been allegations that the dispute process is difficult and stacked against consumers. The FTC report attempts to address that, too.

Of the 262 consumers in the study who disputed information they said was inaccurate:

37 percent said all their concerns were addressed;



42 percent said their report had been modified, but there were still errors on their report;



21 percent said they were unsuccessful in getting their reports modified.



The report did not attempt to establish the veracity of the consumers' disputes.

Credit expert John Ulzheimer, who helped develop the credit score and is now president of Consumer Education at SmartCredit.com, said he felt both the FTC and the credit industry trade group were "embellishing" their claims about the results of the study, but he, too, found the FTC data troubling.

"I'd side with the FTC that the results are more disturbing than they are confirming credit files are accurate," he said. He suggested taking the dispute results with "a grain of salt" because the errors claimed by consumers were not independently confirmed.

FTC Chairman Jon Leibowitz told CBS News, which first reported the study's findings on "60 Minutes," that the results were "highly troubling. ... It's a pretty high error rate."

The credit industry began fighting back even before the "60 Minutes" segment aired. It issued a press release Sunday afternoon, and several employees of Experian spent the evening sending tweets to Twitter users who attacked the industry.

"It's easy to selectively hype snippets from the FTC study to sensationalize the issue," Stuart Pratt, consumer data industry spokesman, said in the release. "But the number important to consumers is the one they ignored – that only 2.2 percent of credit reports contain material errors."

The industry and FTC numbers differ because they describe slightly different things: The FTC says 5 percent of consumers are impacted by a serious credit report error, while the industry derives its 2.2 percent figure from the fact that consumers have three different major credit reports, and often errors appear on only one or two of those.

The industry also disagrees that errors are hard to fix.

"The notion that it is difficult to dispute an error is just wrong. It is irresponsible to suggest to consumers that they might as well not take action when they have a question about their credit report," Pratt said.

Experian public relations officials repeatedly sent out this message last night: "If you ever spot an error on your credit report, please report here http://t.co/5nncPpfP Avg dispute time is 14 days."

It also sent users to the Experian website to read about the firm's policies

"Experian's Commitment to Data Integrity, Customer Service and Consumer Education http://t.co/kejlxpQYvia @ExperianNews"

Some Twitter users complained about Tweet campaign:

"@Experian_US so (you are) responding (to) tweets from US but resolving life changing disputes from Chile and India!Priorities please!!!" wrote @elizabethforma.

As the Red Tape Chronicles and other outlets have reported, consumers disputes are often sent overseas for consideration, and workers in places like India and Chile only have a few moments to consider each dispute.

An Experian official who was sending out Tweets would not agree to be interviewed by NBC News; she directed questions to Pratt at the industry group.