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Is the iPod Shuffle Playing Favorites?
marksilverman writes "Steven Levy at Newsweek is reporting that his iPod Shuffle seems to favor certain songs. Is Apple receiving kickbacks to promote certain artists? Apple denies it, of course, and Levy had the good sense to ask a mathmatician and a cryptographer who explained that it's probably just humans finding patterns where there are none." Less neurotically, both CNet and PCWorld have discussions of the Shuffle's interior spaces.
We actually talked about this in my statistics class today. The professor actually had a friend who could flip a coin and get it to land on whatever he wanted, virtually every time. Made alot of money hustling people with that. It is possible to develop patterns of manipulating 'random' events, through skill of hand (or programming skill), that to most people still look like they're obeying pure randomness, but are actually being subtly manipulated behind the scenes. There's no doubt in my mind it's a possibility that Apple is trying to walk that line.
Or it could be an accident. For example, picture this code:
const int song_id=random()%num_songs;
At a first glance, that might look reasonable; however, once you start to get a lot of songs (and you start to approach RAND_MAX), it will skew your result in favor of low-ID songs.
Who knows if anything is going on here, though.
Don't take a knife to a gunfight, or even a knife to a knife fight. Take a gun to a knife fight.
This page has more information about this phenomenon, called the clustering illusion. Another manifestation is streak scoring in sports, a.k.a. the hot hand in basketball. Players are often though to be "on a roll" when in fact their larger scoring pattern fits a random distribution around a mean.
First, there is the possibility that Apple screwed up the shuffling algorithm -- although not entirely likely. If you ask an introductory programmer to write some code to shuffle an array, you'll most likely get something like this:
for i in range(array_length):
j = random() % array_length
temp = array[i]
array[i] = array[j]
array[j] = temp
This code does NOT produce all permutations with equal probability! Instead, you must use the following code:
for i in range(array_length):
j = i + (random() % (array_length - i))
temp = array[i]
array[i] = array[j]
array[j] = temp
}
This was cribbed from c2 -- see the full article text here for a more informative discussion.
Second, I see a lot of people saying "I have a 20GB iPod -- and I swear sometimes it just NEVER plays this one song." Okay, let's assume that a 20GB iPod holds 5000 mp3 files. What's the probability that you play 5000 songs in shuffle mode, and never hear a particular song?
It's the probability that 5000 times in a row, you hear some other song -- that is, one of the 4999 other songs. Calculating, we get:
(4999/5000)^5000 = 0.3678.
So we have a 36% probability of this happening -- which is not a negligible amount! This will further be compounded by two things: First, you have no way of recalling exactly it has been since you heard a particular song -- if your favorite song was played 1000 songs earlier, it probably feels like 2000. If it feels like 2000, it's probably 4000. Because it's a favorite song, your mind will exaggerate the amount. It's like if you crave nicotine, it can feel like days since you've had a cigarette when it's only been hours. Second, you probably have a lot of songs you would call a "favorite" -- with each having a 36% chance of not being played over the course of 5000 plays, your mind will probably register that at least one of them is "feeling neglected."
Probability is a strange and beautiful thing. Don't expect your average audiophile to understand it. (And I'm not claiming to understand it either, beyond a very cursory level.)
- shadowmatter
> You're absolutely right!@ There's an array inside the iPod shuffle of about 150 artists that will take precedence over all other artists.
Back in late 2001, I wrote a simple program which learns which songs I press "Next(b)" before it completes. Finally after 8 weeks, I realized that I listen to- Eminem and other rap in the morning
- Pop music later into the afternoon
- Rock was for the 5-7 pm slots
- After 10 , it was usually playing Enigma and instrumentals
Was quite different on a weekend with no music on saturdays and often slow Elvis songs on sunday afternoonsQuidquid latine dictum sit, altum videtur
This is got to be a result of the random number generator. Winamp and XMMS are exactly the same in this regard. When my music collection got big enough, I usually just put the player into shuffle mode. It always seems to pick the same songs over and over. Of course, the results are slightly different in XMMS as compared to Winamp.
Of course, I just opened Winamp to test this out and it knows I'm blabbing about it and it's playing music I have not heard in a while.
It would be cool if it didn't suck.