Sunday, July 05, 2009

The Scientific Way of Counting Ralliers

Below are two articles published by the Philippine Daily Inquirer to inform the public about the politics of mass mobilization. Asahan na nating gagamitin ng mga presidentiables ang mga "crowd estimates" para kumbinsihin ang mga botante na malawak ang kanilang suporta and they "have the numbers". I once interviewed Dr. Tapang for my research. The academic is authoritative and and I fully subscribe to his findings and claims.

Measuring the size of crowds
By Giovanni Tapang
Philippine Daily Inquirer
First Posted 01:21:00 06/21/2009

ANNOUNCEMENTS about the size of a crowd after a big mobilization or event are usually as varied as the organizations giving the estimate.

At the Ayala rally on June 10 against a House resolution seeking to convene a constituent assembly (Con-ass) to amend the Charter, we had estimates ranging from a low of 6,000 from the Philippine National Police to a high of 15,000 from organizers.

Politics of numbers

The politics of numbers of a mobilization is obvious, as one story lead last year in the Philippine Daily Inquirer clearly put it: “The crowd is the statement.”

Every time a sizeable mass action is conducted, whether on Mendiola, Ayala or Edsa, conflicting estimates are issued that either downplay or magnify the data. Is there some way to effectively quantify the size of the crowd in a mobilization?

The accepted method for estimating crowd size is to measure the area covered by the protest and the crowd density, and then count the number of those who attended at a certain time.

This estimation is most easily done with overhead shots and aerial surveys. This method was used way back in the late 1960s, when Herbert Jacobs, a professor at the University of California in Berkeley, counted the number of students that can fit within the grid lines of the plaza where students gathered to protest the Vietnam War.

Rule of thumb

He developed a rule of thumb that is still being used in crowd estimation today. A crowd where each one is at arm’s length would cover about one square meter per person.

In a tightly packed, high-density crowd, a person would fill about a quarter of a square meter of space. This means that in these tight situations, four individuals can still comfortably stand and occupy a square meter of space.

There are several other points to consider. Crowd density is usually not uniform, except in very crowded areas, and will taper off from the hub of activity. The time the estimate was made is also important, as crowds are dynamic systems.

Over a period, the crowd size can swell or ebb due to people coming in and out of the assembly area.

Making an estimate at only one point can lead to a different count if it is taken at the peak or near the end of the event.

Assigning marshals to monitor people coming in and out of the hanay (line) would keep a contingent relatively organized.

Militant groups such as those under Bayan have this honed to an art and thus their numbers stay relatively intact until the end of the program.

Ayala area

The Ayala area, where the broad anti-Con-ass mobilizations were held, can be divided into four major areas: Ayala going toward Herrera, the central area of the intersection, along Paseo de Roxas and Ayala toward Makati Avenue and Edsa.

In our estimates, sidewalks and establishments are not included even though there are people who would usually stand there during mobilizations.

The maximum that these areas can hold at 4 per square meter would be about 90,000 people.

If we extend the coverage to the whole stretch of Ayala from De la Rosa to Edsa, the whole of Paseo and Makati Avenue, this maximum can reach 300,000.

Organizers would have different objectives for the mobilizations they organize.

Some events would be a show of force measured in number, while some provide a venue for gathering different political forces.

Edsa Shrine

If crowd size is the target, areas like Edsa or other multiple staging areas would be good places to assemble instead of Ayala.

The central Edsa Shrine-Ortigas area would comfortably contain more than 70,000 and there would be room to expand in four different directions if the crowd increases as it did during Edsa II.


Other assembly points like Plaza Miranda in Manila can accommodate around 5,000 in its central area. The length of Quezon Boulevard from C.M. Recto to Quezon Bridge can hold up to 50,000, while some 35,000 people can fit from C.M. Recto to Mendiola.

Near the foot of Mendiola Bridge, where most rallies are stopped, 5,000 would already fill the area and the central intersection. This estimate excludes C.M. Recto and Legarda and the stretch of Mendiola behind the statue of Chino Roces.

Liwasang Bonifacio

EspaƱa Boulevard from Welcome Rotunda to Lerma can contain a bit more than 100,000 people marching along both directions. If we take only those who will fit from A.H. Lacson to Lerma, the number is around 36,000.

Liwasang Bonifacio, from the National Press Club to Padre Burgos, including the central area, can sustain 46,000 or more if we count people standing under the shade of trees.

Rizal Park

The Katipunan monument’s central area near Manila City Hall would hold 30,000, while Quirino Grandstand and Rizal Park (Luneta) can hold about half a million people. The exposed area of the central quadrangle in front of the grandstand can hold up to 170,000 people.

These estimates exclude covered areas, sidewalks and structures. Due to this limitation, these numbers are in the lower limit of the maximum capacity even if we use a density of four individuals per square meter.


Yet, it is not all about numbers. At the recent Ayala mobilization, what was more interesting was the composition of the rally rather than the size of the crowd.

The groups of religious, businessmen, militants and the political opposition attending the rallies have broadened since a few years ago. Who protested is as important as how many came and participated.

(Giovanni Tapang, a Ph.D., is the chair of the scientists’ group Agham [Samahan ng Nagtataguyod ng Agham at Teknolohiya para sa Sambayanan]. He is an associate professor at the National Institute of Physics in UP Diliman. Calculations used in this article can be found at


How to count ralliers in Luneta
Philippine Daily Inquirer
First Posted 01:27:00 06/21/2009

CROWD estimates of political rallies are often contentious because rally organizers and police estimates vary greatly. As someone put it the estimates usually depended on the political bias of the one doing the counting.

A case in point was the number of people who attended the proclamation rally of presidential candidate Eddie Villanueva on Feb. 22, 2004 in Rizal Park (Luneta) in Manila. It was reported in a newspaper that 2.8 million attended the rally. Other newspapers reported a much lower figure of less than a million.

Gauging the size of crowds at rallies accurately is difficult because the people are usually in constant motion. Densities also vary with respect to the distance from the stage.

In “Chronology of a Revolution 1986,” author Angela Stuart Santiago presents a method of determining crowd density, which, she says, depends on the positions assumed by the people in the crowd.

She presents different positions that characterize a typical rally and the number of persons per square meter based on accepted architectural dimensions.

These positions include a person sitting or squatting and occupying 0.313 square meters; standing, with persons at the sides and directly in front at arm’s length and occupying 0.44 sq m; standing, with elbow room at the sides, front or back and occupying 0.640 sq m; and standing, shoulder to shoulder, no space between people and occupying 0.125.

Based on her estimates, the densest is eight persons per sq m when they are standing shoulder to shoulder, with no space between them. The least dense is 1.56 per sq m when people are standing with elbow room at the sides and at the front and at the back, and 2.27 per sq m when people are standing with others at the sides and directly in front at arm’s length. The average, considering the most dense and least dense positions, is 3.56 persons per sq m.

Getting the total crowd estimate would then entail getting the area and multiplying this with the estimated crowd density.

The entire Luneta Park, for example, from the sea wall to Taft Avenue is 528,832.5 sq m (52.89 hectares). The area, which includes the roads surrounding the park, can accommodate 4.2 million people. That is, if it is totally devoid of structures and if eight people are packed in one square meter, standing with no spaces between them.

But if the average of about three people occupying a square meter is used, a totally barren Rizal Park can accommodate about 1.6 million. But this is an overestimation as at least 8,000 sq m of the area is used for the huge Philippine map, lagoon, fountains, plant boxes, gardens, monuments and poles, canteens and other structures.

Aerial photos of the Villanueva rally showed that his supporters nearly filled up only the grandstand to the Roxas Boulevard area. This has a combined land area of 122,671 sq m. Based on the least dense estimate of 1.56 per sq m and most dense estimate of 8 persons per sq m, the crowd could be as low as 191,367 or as high as 981,368 but still way below the 2.8 million estimate of Villanueva’s supporters.

(This article appeared in the Inquirer on May 7, 2004.)

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