There is a new paper at the OR Forum area of Operations Research. It has been 50 years since the publication of “Little’s Law” (roughly, the length of a queue is the arrival rate rate into the queue times the average wait, so if 5 people per hour arrive into a queue, and the average wait is 20 minutes (1/3 hour), then the average number in the queue is 5/3). This formula is amazing because it holds under very broad conditions. There are lots of applications where you know two of arrival wait, queue length, and waiting time, and Little’s Law lets you determine the third. I spent a half hour today waiting in line at the Alhambra doing Little’s Law in my head (“300 people to be admitted in one half hour slot, one server, 95 degrees, no clouds, looks like 2 people fainting per minute, makes my wait time…”)
John Little has written an article reflecting on 50 years of Little’s Law and Ed Kaplan, Tim Lowe, Sridhar Tayur and Ron Wolff have provided commentaries on the article. Check it all out at the OR Forum.
I tend to be simpler, as in http://www.kproductivity.com/fmwaves/2009/03/26/littles-law-my-sandwich/
Now seriously, this year I gave a course on decision-making and this application was the most interesting, specially when considering there are queues everywhere… as with my sandwich. 😉