How Do the Media and Police Estimate Crowd Sizes?


Keith H. asks: When the police and media report
crowd sizes of a parade or something, what do they base their numbers on? Although the task of determining how many
people attend something as large as say, a political rally or a protest may seem like
a daunting, almost impossible undertaking to do with any accuracy, with some basic information,
it’s actually not that difficult to get reasonably accurate results. The most well-known method of estimating the
size of a given crowd is simply called “The Jacobs’ Method” as an ode to its inventor,
Herbert Jacobs. Jacobs spent a few decades working for the
Milwaukee Journal before retiring into teaching journalism at the University of California,
Berkeley in the 1960s. He thought up his very simple crowd size estimate
method after observing numerous Vietnam War protests outside of his office window. Jacobs noticed that the area the students
stood on had a repeating grid-like pattern, meaning he could very easily count how many
students occupied a certain amount of space by counting how many students on average seemed
to be able to stand inside a section of the grid. By doing this, he soon noticed some patterns. For example, Jacobs found that in the most
densely packed crowds, each person took up approximately 2.5 square feet. We should note that this is the absolute upper
limit of a how dense a crowd can safely get, as in, you simply couldn’t fit more people
into a crowd this dense without someone being trampled or worse, which is probably why most,
including some scholarly articles on the subject we read, simply refer to it as “mosh-pit density”. In a dense, but more manageable crowd, Jacobs
observed that participants had a comparably more roomy 4.5 square feet whilst those in
a “light” crowd had a positively breezy 10 square feet to themselves. In any event, once he had the approximate
average number of students in each grid, he could then easily calculate the number of
grids in an area occupied at a given density, and quite quickly come up with a very good
estimate of how many people were in a given crowd. Thus, the now Gold Standard, and remarkably
simple, “Jacobs’ Method” was born. This may sound like an overly simple solution
but the truth is, it’s strikingly accurate when done by non-biased observers, and modern
technology has only made it easier. For instance, tools like Google Earth have
made learning the exact size and area of a location, as well as dividing an area into
grids, an almost trivial feat for just about anyone. And thanks to ubiquitous media coverage, any
large gathering of people is going to have video or photographic footage (if not just
scanning the Tweetosphere for people in the crowd who may have gotten a good shot and
posted it online). So breaking things down from there is relatively
trivial. Of course, one could get really fancy and
take a photo of an entire crowd and use a bit of custom designed image processing software
to programmatically count the people in a crowd for a more exact number, but the extra
level of accuracy here over the properly executed Jacobs’ Method isn’t really typically that
much, nor all that necessary. Of course, when giving estimations, sometimes
the news media or the organisers of an event do like to fudge the numbers a bit. Perhaps the most famous example is that of
the Million Man March- a mass gathering of black Americans (mostly men) that took place
in 1995. As you can probably guess from the name of
the march, event organisers afterwards were very insistent that at least a million men
had attended, with estimates going as high as two million. However, the National Parks Service disagreed
and offered up a much lower, but still extremely significant figure of around 400,000 individuals. But when something is called the Million Man
March, 400,000 seems a bit of a letdown, even though it’s logically very much not; getting
400,000 people (about 1.2% of all black Americans in the United States at the time) to show
up at such an event in Washington DC is really quite a feat. Nevertheless, the NPS’s estimate incensed
a key player behind the march, Louis Farrakhan, so much so that he threatened to sue the NPS. As a direct result of the brouhaha that followed,
the NPS is now banned by congress from estimating the size of crowds in Washington, at least
publicly. As they noted, if the President asks them
for how big a crowd was, they’re happy to crunch the numbers given footage of the crowd. They just aren’t technically supposed to use
tax payer dollars in this way anymore, so wouldn’t share that information with the media
who, of course, could quite easily come up with their own estimates. So how many people actually attended the Million
Man March? While an exact figure is impossible to discern,
most researchers are in agreement that the original estimation of the NPS is pretty accurate. For example, in 2004 a pair of researchers,
Clark McPhail and John D. McCarthy, worked out that in the location of the gathering
there would have been space for a maximum of 1,048,206 people assuming that every inch
of the crowd was as densely packed as safely possible at 2.5 square feet per person. In the end, from the pictures available of
the gathering, they determined that the NPS’s estimate of about 400,000 was quite accurate. This isn’t a one-off case either; research
has shown that the estimates of event organizers are consistently higher than those of the
police, who tend to give more accurate predictions given the events generally take place in gathering
spaces that are well documented in case of emergency, in terms of how many people they
can safely hold. Of course, event organizers (and sometimes
the media) can have something to gain by overstating how large a crowd is, while the police and
other official agencies generally do not. That said, there are certainly examples out
there of official agencies intentionally adjusting announced crowd sizes for one reason or another
just like organisers love to do. Luckily, there’s a simple method of accurately
estimating the size of a crowd that’s free from bias, and these days can be easily done
even just by some guy sitting at home in his PJs surfing the web half way across the world
from where the event is actually happening, which is more than a little amazing. Don’t you think? Bonus Fact:
• The “cheerleader effect,” the theory that people look more attractive in groups,
has been around for ages. In 2013, research by Drew Walker and Edward
Vul of the University of California (published in Psychological Science) demonstrated that
this is actually true; people do report others looking more attractive in groups than when
seeing the same individual without others around them. As to why this happens, they proposed it is
because, “(a) The visual system automatically computes ensemble representations of faces
presented in a group, (b) individual members of the group are biased toward this ensemble
average, and (c) average faces are attractive. Taken together, these phenomena suggest that
individual faces will seem more attractive when presented in a group because they will
appear more similar to the average group face, which is more attractive than group members’
individual faces.”

100 thoughts on “How Do the Media and Police Estimate Crowd Sizes?”

  1. So this channel dispels and belabors the million man March as not being even half of that numbers wise but doesn't address the dumbo at 1500 Pennsylvania Ave bloviating. Ad nauseum about the inaugural crowd size for 3yrs running?

  2. I just took econometrics, I can answer this for you. Take a random sample from the crowd and see how large it is. Then scale it up to match a base estimate of the crowd size. Done

  3. Oh the Media have an interesting technique for sure. But they need to know who is hosting the event before they can give you a number.

    If it's someone they don't like, such as Trump, then they just say a quarter of what everyone was expecting, take a picture 2 hours before the event begins and that's it.

  4. If it's left wing . then use science then multiply by ten. If it's right wing, then use science then divide by ten.

  5. Adding to the complexity is that the number of people in a crowd is rarely the number of people participating. In the HK protests for instance, people are arriving and leaving in a constant stream. The number participating in a protest at one given moment could be just a fraction of the number of total participants, and at the same time many participants move between different protest locations making it difficult to estimate the total number unless all counting is done at the same time.

  6. I went to the march for our lives in March 2018 in DC, and watching the news later they said there was 800,000 people there. I've always wondered how they did it.

  7. Is it the same method used for estimating how much you can stretch a video length?

    Turns out no, but you get the idea.

  8. Ironically the Moshpit is the least densly packed are in the crowd, the densest areas are actually the areas just next to the Moshpit 😂

  9. They base the numbers on whatever bullshit narrative they are trying to push. For example:
    Anti-Brexit march, the media reported a million people turned up. It was actually less than 300K.
    15,000 people marched against Tommy Robinson. Actual numbers were about 3000.
    "a few thousand" people marched with Tommy Robinson. Actual number was near 50K.

    The police may know how many people there actually are so they put the right number of cops on the job. However, the actual number released by the media is made up to sell their political view.

  10. Group attractiveness is explained by faces. Graphic representing this? A bunch of cheerleaders backsides posted on the screen

  11. I enjoyed that stock video of silhouettes at a concert. I like to think it's just you and staff dancing in front of a green screen.

  12. I was waiting for a reference to Trump's inauguration the whole video… you must have discussed including it, no?

  13. I have an idea for a video: The “Eye of the Sahara” is looking more and more like a good candidate for the ancient city of Atlantis. All you have to do is see the numerous YouTube videos on the subject. Those videos sound VERY compelling, yet it is never mentioned in any article or video on Atlantis (outside of the Eye of the Sahara videos). Could you give me you opinion on the subject?

  14. So THAT is why K-Pop groups have so many fans! The more members they have, the more attractive they become!

  15. Mr. Whistler I’m a big fan of all your shows. I have a question for the “Today I found out” series. It’s a bit silly but here it goes. What is the history of the rubber duck, also why a duck of all things? I had one as a child with a little Sailor hat on its head I called Sailor Quacky that I took to the bathtub, into the backyard pool, etc. Sailor Quacky met his end from our dog and he was chewed to bits. That’s when I found out Quacky was plastic and not rubber. Were rubber ducks ever rubber? I’m puzzled.

  16. The correct answer is "poorly", followed closely by "manufacturing a number that is politically expedient".

  17. how come people share habits such has taking their pointer finger and thumb and rubbing it once over their mustache area when id say confused or stressed

  18. Louis farrakahn. . . Well those people have been fucking everything up since before my time. This was so fucking sweet to hear.

  19. I don't know about cheerleaders being more attractive because they're in a group. I'd be more inclined to think the attractiveness is more related to wearing crotch-high skirts or ultra-skimpy shorts, and a fair amount of cleavage. With apparel like that, even plain girls can look pretty hot.

  20. Still, estimates like this are the tip of the iceberg. We're so used to the unchallenged estimates of 'modelling software' that they're notoriously easy to fudge. Read any day's news coverage to see 'how many plastic bags our policy has saved from landfill', 'how much money this policy will save/make the taxpayer', 'what today's weather forecast says', 'how many people are rorting welfare…' Neither media nor government are accountable for what are often WAGs (Wild Arsed Guesses) and they ALL chose the modelling software that gives them the answer they want.

  21. Here is an idea for a video. why do British pronounce "lieutenant" as "leftenant" when there is clearly no 'f' in the word at all. I have noticed many words that they add an extra letter to that just isn't there. An example would be soda being pronounced as "soder' or methane pronounced as /meeth -ane/ rather than /meth – ane/. It just seems a bit odd to me.

  22. So true about the group thing. Every time I go out with my frumpy homely looking friends.(They'd be the first to admit it.) I never go home lonely. By myself, I'd have an easier time pulling a splinter from Bigfoots infected toe!

  23. Count like the Trump administration, and just state the number that you want to be present !
    This is not hard….

  24. @todayifoundout why do men wear long socks with dress suits? If you're wearing long trousers why must the socks be long? Where did this rule come from? I've wondered this since I was a kid. 🤣

  25. Can someone tell me how in medieval period count the enemy's army?

    Like, how did they know that a 30,000 troops is marching towards them, or something likr that.

  26. Hi Simon, love your vids. Quick question, can I assume that this video is a node to affirm that the Hong Kong protestors’ estimate of 2+ million people is an exaggeration, and that the police estimates of 300K+ people is the accurate number?

  27. It depends if they’re talking about a pro-Democrat crowd or a pro-Republican crowd!
    For a Democrat crowd you count the pixels on the screen and multiply by 100,000. For a Republican crowd, it’s just "sparse".

  28. I'm not sure if this is where i ask a question, but how do rivers get theiir water, it makes no sense to me how they dont run dry

  29. Great video as usual. Just one thing. It's. FARE AH KON. not Farr-Ah- kin. Not slamming your distinguished accent just pointing it out.

  30. This was a video that BEGGED for a review of Trump's inauguration, which was hotly debated by Trump VS Everyone.
    Great effort not "going there".

  31. It is like counting gumballs in a bowl. If there is no receipt? It is just a guess. Bottom line. They all lie depending on what they want to be there.

  32. Feel bad for the guy at the NPS who had the right number but still got shafted by groups who wanted to fudge numbers… poor guy probably tells his grandkids about it

  33. No one gives a sh!t about the million man march. I guarantee we all clicked assuming a breakdown of the last inauguration.

  34. I do ensemble perception research and while crowding is somewhat related to ensemble perception I didn't expect to see you talk about my research field at the end.

  35. Easy; the media uses their standard formula. A Republican crowd of ten thousand is reported as one thousand, A Democratic a crowd of one thousand is reported as ten thousand.

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