Numbers for Saturday's massive Women's March Los Angeles were all over the place. Organizers claimed 750,000 people, a figure that would have overshadowed a 500,000-strong, pro-immigrant march in 2006. City police and fire officials said over the weekend that approximately 100,000 people had hit the streets of downtown L.A. That number didn't seem right to many participants who couldn't get on packed trains, let alone through the car- and pedestrian-clogged streets leading to the Civic Center.

Compounding the range of figures was one more, 500,000, that appeared in the Los Angeles Times' initial coverage of the march. That stat, along with 750,000, was widely echoed in reports across the nation and likely helped inflate national estimates of the number of people who took part in demonstrations widely seen as a repudiation of the anti-woman, anti-immigrant policies of President Donald Trump.

The Los Angeles Fire Department revised its number upward to approximately 350,000 participants, LAFD public information director Peter Sanders said late yesterday. So how did organizers come up with 750,000, and how did other reports cite 500,000?

Speaking for organizers over the weekend, Cherry Hepburn of public relations firm Putnam & Smith said, via email, “It came from LAPD and LAFD.” Yet those departments consistently told reporters Saturday that the number was more like 100,000. “To my knowledge we did not provide any crowd estimate to the organizers,” LAPD Capt. Andrew Neiman said via email.

On Monday, Hepburn said officers at a command post told organizers at 2 p.m. Saturday that police were estimating a crowd size of 750,000. That morning, she said, the same officers said there were approximately 250,000 people at Pershing Square, where the march stated, and another 250,000 at City Hall, where it eventually ended. The crowd swelled throughout the day. “I have since heard that they may upgrade the number,” she said yesterday, “but [I] cannot yet confirm that.”

A Times report simply compared the Saturday crowd to the 500,000-strong 2006 march, but the way the paragraph in question was structured led many to believe the number belonged to Saturday's affairs:

The Los Angeles Police Department said in a statement that “well past” 100,000 people attended but did not provide a more precise number. Officials said it appeared to be the largest demonstration since a massive 2006 immigration march downtown. The LAPD estimated that march drew 500,000.

(Emphasis ours.)

That story was front-and-center on the Times' homepage Saturday afternoon and featured a headline deck that said, “The LAPD estimated the march drew 500,000 … “

Another version of the Times' homepage that day cited estimates of 200,000, which apparently made it to a national Women's March spreadsheet, compiled by two political science professors, that's being touted as one of the more comprehensive and scientific accounts of Saturday's turnout.

Meanwhile some publications, including Time, picked up the 500,000 number. The 750,000 figure seemed to loom the largest, however. Local television stations (ABC Eyewitness News, NBC Southern California) and Hollywood trade publications (Variety, Deadline) ran with it. Even the city's second-largest daily newspaper, the Daily News, went with 750,000.

Organizers of big events and their beneficiaries have motive to exaggerate (we're looking at you, Mr. President), and news reporters are trained not to trust them. For example, promoters of music festivals and large concerts have sometimes inflated attendance; it stokes expectations and ticket sales for the next event.

In any case, experts, including experienced police who have helicopters at their disposal, say estimating large crowds is largely a guessing game. “Crowd-size estimation is a murky science, positioned at the intersection of statistical precision and political sleight-of-hand, and plenty of people are motivated to either exaggerate or low-ball an event's attendance,” according to a Popular Science story on the art and alchemy of crowd estimation.

“We generally avoid providing crowd estimates and leave that up to the event organizers to provide,” LAPD's Neiman said. “We have been criticized in the past for providing crowd estimates which are in conflict with the event organizers', so we have a general practice now of not providing crowd estimates.

“There is no exact science when the crowds occupy open areas such as streets,” he said. “Any crowd estimates are just that, estimates based on a best guess. There may be formulas that are used to calculate crowds, but I am not familiar with them and we generally do not use such formulas as a practice.”

But during contentious political times — when Trump is falsely claiming up to 1.5 million in attendance at his inauguration and his administration is floating the bizarre concept of “alternative facts” — it's important to try to determine some sense of reality. Alternative facts battling alternative facts doesn't get us there.

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