If you have ever strained to count a crowd of people milling around a concert, parade or festival, you know how hard it can be to get an accurate head count.
The difficulty of crowd counting came up briefly at an IRE and NICAR Advanced CAR Statistics Boot Camp at Arizona State University, and I learned there is a way to go beyond official estimates and find a more accurate estimate for readers.
Within days of my completing the Boot Camp, editors wanted to find a way to accurately count the number of people that attended La Fiesta de los Vaqueros Rodeo Parade.
Touted as the world's longest, non-motorized parade at a length of 2.1 miles, it marks the beginning of the Tucson Rodeo, the first event of the season on the U.S. professional rodeo circuit.
Organizers say the parade and the events over the ensuing days are a major economic boon to the community with an estimated 200,000 people attending the parade alone every year.
As a native Tucsonan who had never been to the rodeo or the parade, I found that figure hard to believe. It meant that as many as one in every four people living in the county attended the opening day event.
Last year, our count put attendance at roughly a third of the parade committee's official estimates, which ranged from 175,000 to 180,000.
Stats camp instructor Steve Doig, a professor at Arizona State University, talked about several different methods of approaching the problem, including using of aerial photography and software designed specifically for the task.
We decided the parade did not warrant the expense of chartering an airplane or purchasing software. Instead, I opted for a notebook, an Excel spreadsheet and my mountain bike.