Department of Veterans Affairs Secretary Eric Shinseki says the agency made progress this year in reducing the claims backlog that has regularly caused heat from some veterans groups and lawmakers.

According to the VA's annual Performance and Accountability Report released last week, the Veterans Benefits Administration hit key milestones in 2013, which puts it on track to end the chronic claims backlog by 2015.

"As of September 30, 2013, the claims inventory totaled 722,013, down from a high of 883,930 in July 2012," the report states. "Of that inventory, the backlog -- those claims older than 125 days -- was 418,472, nearly 193,000 below the peak backlog in March 2013."

The same report also states that as of this past August the accuracy rate of decided claims was just over 89 percent.

That figure is just a percentage point shy of the one Under Secretary for Benefits Allison Hickey presented earlier in the month to the Senate Veterans Affairs Committee. Then, Sen. Richard Burr, R-NC, the committee's ranking member, expressed serious doubt over the figure, pointing out that other backlog trackers put the error rate significantly higher in some cases.

The American Legion, which partners with the VA in assisting vets with claims applications and also conducts its own accuracy surveys, put the error rate at 55 percent during 2013.

Others, including the VA's Office of the Inspector General, have arrived at other figures, but none coming up to the claim made by the VA.

During the Senate hearing, Hickey said the Legion numbers were right for the way they figured them, but said the VA numbers are validated by an independent group, the Institute for Defense Analyses.

Zach Hearn, deputy director for claims for the Legion's veterans' affairs and rehabilitation division, said he understands why the VA would be upset over the Legion's numbers.

"Here they're sitting with a 90 percent accuracy rate and someone says: 'hold on, here's what we've discovered,'" Hearn said.

The Legion's review over the past year of 260 claims decided at eight VA regional offices concluded that 55 percent had errors -- meaning an accuracy rate of 45 percent, or half of what the VA claims.

The OIG, in a review of 46 claims from the VA Regional Office in Newark, N.J. this past year, found errors in 21 -- nearly half.

The VA says its own review of claims is far broader than those done by the Legion and the IG. For one thing, the Legion is only able to review claims it has consent to look at.

The VA uses an internal program, Systematic Technical Accuracy Reviews, or STAR, to review a random sampling of claims completed at each of its 56 regional offices. Beyond that, the VA's work is reviewed by the Institute for Defense Analyses, which Hickey argued validates the department's findings.

Brandon Friedman, the VA's former director of online communications and author of "The War I Always Wanted," defended the VA's figures after the Senate clashed over stats.

"One (VA) uses a random, statistically significant sample of claims. The other (American Legion) uses a non-random, biased sample of claims," Friedman said on Twitter.

Friedman, who is now a vice president with the public relations firm Fleishman-Hillard and a fellow at the Truman National Security Project, said in a later interview that any lawmaker can ask VA to explain its methodology as well as its data.

"How quickly they get it typically depends on the complexity of the request," he said.