The organizations analyzed credit scores in 502,623 merged credit files and reviewed files of more than 1,700 individuals, maintained by the three major credit repositories: Equifax Inc. in Atlanta, Ga.; Costa Mesa, Calif.-based Experian Information Solutions Inc.; and Trans Union LLC in Chicago.

The study said it found a significant discrepancy among scores from different credit repositories--an average range of 41 points in the scale of approximately 400 to 800 points in the mortgage-lending scoring model.

A further analysis of 51 representative files for consistencies and inconsistencies revealed reasons for these differences in scores, according to the study.

The biggest factor was common errors of omissions, including the failure to report a negative event, such as a delinquency or charge off, or a positive event, such as payments on an account.

The analysis found that nearly 80 percent of the files were missing a revolving account in good standing while one-third were missing a mortgage account that had never been late.

"You can conclude from these findings that a significant number of people are misquoted and adversely impacted in their auto and home insurance," said Robert Hunter, director of insurance at CFA.

Mr. Hunter suggested that insurers should immediately provide consumers who suffer adverse actions from their credit reports a free copy of the reports that were used for the decision. And if inaccuracies are found, insurers should quickly reconsider their decision.

"If an insurance agent says rates would go up because of bad credit scores, you should get a copy of your scores right away," he said. "People shouldn't be paying higher rates for errors, and we found that such errors were significant at all levels."

Under the Fair Credit Reporting Act, insurers that use credit reports are required to tell consumers that they have the right to get copies of their reports. But the process to request them and challenge their accuracy can take months, "so you might as well forget it for a six-month auto insurance policy." Mr. Hunter said.

He said the Federation believes "consumers should be able to get a copy right away, and the whole thing could be done in a day or two."

In addition, consumers can take preventive steps to reduce the chance of unfairly receiving adverse actions such as being charged higher premiums, according to CFA.

The groups advised that consumers should maintain consistency in credit applications by using their full legal name. And insureds should also review their credit records regularly by purchasing credit reports and scores from major credit repositories once a year and disputing any errors that appear on their reports by contacting the relevant credit repository.

"This frequent huge discrepancy in scores reveals the importance of consumers being able to quickly learn of and correct inaccuracies," Mr. Hunter said.

In response to the report, one of the credit firms suggested the number of files analyzed might be too small to offer many meaningful conclusions.

"The study had various parts to it--the total number of files examined ranged up to half a million. But it looked at only 51 files to analyze consistencies and errors of omissions. If the number of files was bigger, results could have been different," said Donald Girard, public relations director at Experian.

"Even 500,000 credit files are only one-fourth of one-percent of the size of our database, which has 205 million files. The same is true for Equifax and Trans Union. We haven't had our statisticians look at the study yet, but the study size is very small, so any extrapolation must be done with care," Mr. Girard said.

He added that the system "is governed by the Federal Trade Commission, and it has been complimentary about the system as it is currently configured.It doesn't mean that we are not improving it everyday. Of course we are. We are improving it on a daily basis--we always have been."