Lazy option is best when waiting for the bus

Saturday, 26 January, 2008

Lazy option is best when waiting for the bus.

Buses travel in packs. It’s a universal constant. So if you’ve just missed a pack of buses that were meant to be travelling 20 minutes apart, what should you do? Wait for another bus-pack, or walk to your destination?

Scott Kominers, a mathematician at Harvard University, and his colleagues derived a formula for the optimal time that you should wait for a tardy bus at each stop en route before giving up and walking on. “Many mathematicians probably ponder this on their way to work, but never get round to working it out,” he says. The team found that the solution was surprisingly simple. When both options seem reasonably attractive, the formula advises you to choose the “lazy” option: wait at the first stop, no matter how frustrating.

There is an exception to this rule however, and is something I’ve discovered along the way. The hard way, might I add.

The formula does break down in extreme cases, Kominers says, when the time interval between buses is longer than an hour, for example, and your destination is only a kilometre away.

A kilometre is probably a five to ten minute walk for any able bodied person after all.

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