Even though the 5 million attendees estimate for the Cubs parade and rally was widely shared after being made by city officials, there is good reason for reconsidering the figure:

“The guesstimates are almost always vast exaggerations,” said Clark McPhail, a sociology professor emeritus at the University of Illinois at Urbana-Champaign.

Politics often play a factor in overblown crowd counts. Runaway enthusiasm also could pump up the final tally, McPhail said.

There is a science to calculating crowds. The most common method is to draw a grid and make an estimate based on the average number of people that would fit into each section.

Another way to gauge crowds, particularly in a city such as Chicago, would be to analyze the capacity of buses or trains to deliver millions of people downtown or along the parade route, according to Steve Doig, the Knight Chair in Journalism at Arizona State University.

It doesn’t seem like it would take too much to draw a better estimate: there are plenty of aerial shots of the parade route and rally and groups like Metra and CTA could share figures.

Perhaps it isn’t a matter of examining the data: perhaps few people want to. Chicago could use some good news these days and making such a lofty estimate – supposedly making this the seventh largest peaceful gathering of people in human history – can boost the city’s image (both internally and externally). The team probably doesn’t mind the figure: it illustrates how dedicated the fans are (though there are plenty of other ways to do this) and might help increase the value of the franchise. The fans like such a figure because they can say they were part of something so much bigger than themselves.

If a revised lower figure gets released, I suspect it will not reach much of an audience.

Sociologists with their interests in social movements have been at the forefront in estimating crowd size. See earlier posts about counting crowds here and here.