CAUSE AND EFFECT
In an article sub-titled "Drilling Down", this New York Times piece covers a Forrester survey that tries to make the point that "Sales of iPod and iTunes Not Much in Sync". Here's the crux of their argument:
At any given point, the cumulative number of songs sold by the iTunes store has generally been about 20 times the cumulative number of iPods sold, according to Forrester Research, the technology consulting firm. That ratio has recently crept up to roughly 22 to 1, as 1.5 billion songs have been sold. The figures were compiled from public statements by Apple.
The numbers suggest that iPods are not driving iTunes sales as much as early supporters may have expected."
There may be another reason for the "slip" in the 20 to one ratio though.
With 67 million iPods 1.5 billion iTunes songs sold as of September this year, the piece calculates that there are now 22 iTunes songs sold for every iPod sold vs. the historical 20 to one ratio.
But we need to keep in mind that many an iPod user now has more than one iPod. More than likely this user has a hard disk based iPod, along with a flash memory based iPod like the Nano and/or the Shuffle.
This means that the same library of songs, from iTunes are not, are spread out over more than one iPod for that user. His/her rate of song acquisition may stay the same, yet the ratio between songs and iPods will naturally widen.
I don't have access to the breakdown of the various types of iPods. But if you assume for the sake of discussion, that Flash-based iPods were 15% of the total, then one could adjust the 1.5 billion songs down to 1.275 billion "iPod equalized" songs. Dividing the new number by 67 million units, brings us back roughly to the 20 to 1 ratio.
So this theory may offer another explanation for the statistical trend cited by the New York Times. Just a thought.