LIFE ON RANDOM

oh no, another air supply song?
Like many, when I've listened to any large musical library on my iPod or just off my computer's library of songs, I always have wondered if the "random" function is really all that random. After all, how many of us have had that experience where, on "random," we still hear three songs from the same album within half an hour of each other. Wired's Dan Goodin wondered the same thing and sought out some scientific help to explain the phenomenon. The short story is this: the problem isn't the playlist: it's us. (Alternatively: it's not computers at fault, it's the human users).

Goodin spoke to mathematician Jeff Lait who specializes in randomization:

"Lait referred to a phenomenon statisticians call the birthday paradox. Roughly stated, it holds that if there are 23 randomly selected people in a room, there is a better than 50-50 chance that at least two of them will have the same birthday. The point: Mathematical randomness often contradicts our intuitive expectations of randomness."

What Lait explains is that our expectation isn't that things be wholly random since, randomly speaking, it's perfectly mathematically reasonable for multiple songs by the same artist to show up close to one another. As far as the science is concerned, that's random but our perception is that this is too many similar songs in a row. Instead, Lait suggests that what we really want is a playlist that's:

" ... stratified, or separated into categories that are weighted by a listener's preferences. A stratified playlist might select songs randomly but would be smart enough to throw out choices that, say, would repeat a band within 10 songs."

In other words, a stratified list would conform to our expectation and perception of randomness even if, technically speaking, we're actually giving programming instructions that would seem to be the opposite of what the point of randomness is. But hey, so long as you're happy with your playlist at the end of the day, it's all good.

--O.W.