Steve Levy has a fascinating article in the Guardian "Weekend" magazine today called: "Oh No, Not Steely Dan again".
It relates examples where the "random" shuffle on the iPod doesn't seem so random. In fact, there have been reports of the shuffle mechanism taking on human characteristics or, going further, assuming the feelings of the iPod owner...Steely Dan tracks appearing every 10 minutes, even though there are only 50 Steely Dan tracks amongst 3,000 odd songs on the iPod...Examples of people thinking of a song and "shuffle" producing it next..."Blue" songs appearing when the owner is feeling melancholy and "up" songs appearing when the owner is feeling energetic..etc..etc...
I myself have had similar experiences. Whatever I seem to do, Barenaked Ladies seem to crop up every three tracks, despite having only one album's worth amongst 1,000 tracks on my nano.
Steve Levy, in an extract from a book on the subject called "The Perfect Thing: How the iPod Shuffles Commerce, Culture and Coolness", beautifully explains the whole thing.
In essence, the iPod shuffle mechanism is about as "random" as you can get within the constraints of PC hardware. To get more "random" you would be into the "quantum behaviour of atomic particles" etc etc. 'Nuff said.
The problem is not the iPod "shuffle" facility, but our perception of randomness. Certain things stand out to us, and therefore we assume that the shuffle is not random. We keep hearing Barenaked Ladies tracks and that is all we remember, so they stand out and we assume that the shuffle is not random. In fact, it is our perception which is at fault, not the shuffle. (In a truly mathmatically random selection you will indeed find the same artist appearing frequently.)
So much so, that in 2005 Apple introduced "smart shuffle" so, by using a scroll bar, users can control "how likely they are to hear multiple songs in a row by the same artists". In the words of Steve Jobs, of Apple, "We're making it less random to make it feel more random."
Sounds strange, but it is true.