Last Saturday, protestors marched in London to call for a ‘People’s Vote’ on the final Brexit Deal. The organisers claimed that 1 million people marched, and that figure was repeated by a numberofnews outlets. We’ve been asked by readers to check this claim.
The reality is that it’s hard to precisely measure crowd sizes at non-ticketed events. That said, experts in crowd estimation have said the crowd on Saturday was less than half the size estimated by its organisers.
Talking to Wired magazine, Manchester Metropolitan University’s Professor Keith Still, said “based on the visuals from the helicopter image, it’s between 312,000 and 400,000 people.”
This type of crowd estimation, called the Jacobs method, is done by dividing a crowd site area into sections, measuring the size of each section and then multiplying each area by the estimated density of people within that subsection.
How did the People’s Vote estimate 1 million?
The People’s Vote said they estimated the size of the crowd using information from staff and volunteers as well as examining aerial pictures from helicopters.
They said that “peak crowd densities were estimated at 4.5 people per square metre”. (For context: Professor Still says the average crowd has between two and four people standing per square metre, and anything more than four people per square metre becomes too uncomfortable to move).
You’ve probably seen a surge in misleading and unsubstantiated medical advice since the Covid-19 outbreak. If followed, it can put lives at serious risk. We need your help to protect us all from false and harmful information.
We’ve seen people claiming to be health professionals, family members, and even the government – offering dangerous tips like drinking warm water or gargling to prevent infection. Neither of these will work.
The longer claims like these go unchecked, the more they are repeated and believed. It can put people’s health at serious risk, when our services are already under pressure.
Today, you have the opportunity to help save lives. Good information about Covid-19 could be the difference between someone taking the right precautions to protect themselves and their families, or not. Could you help protect us all from false and harmful information today?