# TWSB: Do the Hustle! Er, Shuffle. Do The Shuffle. iPods. This post is about iPods.

So I found this NPR transcript this afternoon discussing a listener’s question about the “shuffle” feature of iPods. Specifically, what the mathematics behind the shuffle feature are. After all, the listener notes, it sometimes seems like the same songs keep coming up while many others are never played.

Keith Devlin, executive director of the Center for the Study of Language and Information at Stanford, answers the question. The shuffle, he says, is meant to be random and in fact actually behaves as a random event. Mr. Devlin explains that people have difficulty recognizing randomness because of the simple fact that one of the features of truly random selection is the repetition of patterns. He uses the example of coin tossing. If you toss a coin twenty or so times, you’re very likely, he says, to get streaks of the same side coming up, like a streak of five heads or something. We tend to see such streaks as non-randomness, though, because such patterns surprise us (after all, it does seem intuitively weird to see five heads in a row when you’re tossing a coin when you know that both sides of the coin have an equal probability of occurring. The magic of independent probability!).

Mr. Devlin concludes, “so, assuming that Apple have designed a really good randomizer in the iPod, then you are going to start getting repeats of songs and you are going to find that some songs don’t come up seemingly for a long time. That’s the way random behavior is.”

Cool, huh?

30-Day Meme – Day 15: A poem you wrote.
I wrote this poem for my grandpa the night before he died of a rare cancer. I remember reading it to him and watching him slowly fade in and out of consciousness. Everything in this poem is totally true of him. You rocked, grandpa!

A Grandpa is someone you can count on in a mess
Though with woodworking and painting he is easily obsessed
Not a job too tough
Not a place too rough
For this daring man of a ripe old age
Who has lived in the past and seen the future.
Can re-fix a shoe with a single suture.
No need to ask for directions
Full of funny imperfections
This daring man of a ripe old age.
Whether zooming to the store for his lottery ticket
Or checking the numbers—did he win it?
Doesn’t complain
Need I explain?
The daring man of a ripe old age.
The daring man of a ripe old age.

### 2 responses

I remember that my old iPod had a smart shuffle feature, where it wouldn’t play two songs by the same artist in a row, and wouldn’t play two songs with the same title in a row. While that did cut down on the true randomness of it, I personally thought it was a better listening experience, since my new iPod seems to go on single artist kicks sometimes.

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1. Haha, my iPod classic gets obsessed with a single artist every once and awhile, but my Touch doesn’t do that very often.

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