Following up on Nate Silver's assertion that in his experience, the fact-checking process at Sports Illustrated is more rigorous than in the political media ...

One way in which news organizations frequently drop the fact-checking ball is by repeating as fact something that they do not independently know to be true, but that has been reported elsewhere. Making matters worse, they often subtly change the initial report, and a game of telephone ensues.

A correction published in today's New York Times hints at one such occurrence. On Saturday, the Times reported:

[O]n Thursday, Mrs. Clinton was spied boarding a plane to Chicago -- on ''personal business,'' a spokesman insisted -- and by early evening a small motorcade of black sport utility vehicles emerged from the garage of the downtown Chicago building where Mr. Obama has his transition office, just minutes before Mr. Obama's own motorcade left it. Mrs. Clinton, as a former first lady, has Secret Service protection and travels in a government S.U.V. By Friday morning, amid escalating speculation that she was a serious candidate for secretary of state, associates of both of them confirmed they had met.

Today, the Times issued a correction:

A Political Memo article on Saturday about a trip by Senator Hillary Rodham Clinton to Chicago ... misattributed the statement that Mrs. Clinton went there on “personal business.” The comment was from media reports, which turned out to be wrong; it was not made by Mrs. Clinton's spokesman. (Mrs. Clinton's office said only that she had no public schedule on Thursday.)

The “personal business” line appears to have originated with a report by NBC's Andrea Mitchell on the November 13 Nightly News broadcast: “Hillary Clinton was seen taking a flight to Chicago today, but an adviser says that was on personal business."

Not only did the Times initially adopt Mitchell's reporting as verified fact, it embellished a bit, turning her report that a Clinton advisor said Clinton was in Chicago on personal business into a spokesman insisting that was the case.

The Times does not seem to have been the only news organization that adopted Mitchell's reporting as fact, or the only outlet that embellished the report. Some went so far as to suggest that a specific Senate staffer had been dishonest with reporters.

(Given the vague attribution, it is impossible to be certain that the following examples were based on Mitchell's report -- or other repetitions of her report. But it appears likely that they are.)

Just a few hours after Mitchell's initial report, MSNBC's Keith Olbermann appeared to be referencing it when he told Countdown viewers “It is insisted by a Clinton advisor that this was personal business..."

So now the “Clinton advisor” isn't merely saying Clinton's trip to Chicago was “personal business”; he or she is insisting that was the purpose.

The next day, November 14, Reuters seems to have modified Mitchell's report a bit more: “Clinton was described by her office as having flown to Chicago yesterday on personal business.”

Keep in mind that Mitchell's original report was that a Clinton “advisor” said she was in Chicago on personal business. The Clintons have many “advisors”; Mitchell's source could have been any number of people. Indeed, on the morning of the 14^th, Mitchell clarified her report via MSNBC's First Read that her source was not Clinton's “office”:

NBC's Andrea Mitchell reports that Clinton's Senate office never confirmed to NBC that Clinton was in Chicago; it was another Clinton adviser who did so. Clinton's Senate office referred Mitchell to the Obama transition office.

Nevertheless, Reuters shifted the sourcing to Clinton's Senate office, as though it were an official statement rather than what may have been nothing more than an offhand, background comment by an advisor who didn't have complete information. That same day, November 14, the New York Post similarly reported that “aides insisted she was on personal business.”

That construction quickly made it halfway around the world - literally. An Australian Broadcasting Corporation reporter told viewers on November 14, “We're told that she is actually in Chicago for what her office describes purely as personal business but of course that's simply added to the speculation.”

On November 15, the Times of London got even more specific, attributing the “personal business” statement to Clinton's “spokesman” - and, in the process, suggested he was lying: “Although Mrs Clinton's spokesman would say only that she was travelling on 'personal business', sources yesterday acknowledged they [Obama and Clinton] had held private talks.”

Also on the 15^th, Australia's Daily Telegraph reported that aides to both Obama and Clinton claimed she was in Chicago on “personal business”: “Adding to the intrigue, Senator Clinton was seen aboard a flight to Senator Obama's hometown of Chicago yesterday, but aides from both camps insisted she was on personal business.”

All of which led to CNN Reliable Sources host Howard Kurtz suggesting on air yesterday that somebody was lying - based on nothing more than what “sources” supposedly said:

KURTZ: [S]ources told journalists that Hillary Clinton was in Chicago on personal business. Well, it turns out that she met with Obama and they did discuss either this job or possible jobs. So isn't that -- the technical term, I guess, would be lying?