Why are some things less popular than others? There are lots of reasons, of course, but the two I've been focusing on most in my research are the breadth of their appeal and their age. Things of broad appeal tend to sell better than things of narrow appeal. And new things tend to sell better than old things.
If you've been reading any of my work you'll know that I'm quick to emphasize that there's little connection between those two factors and the underlying quality of the product in question or the extent to which someone will be satisfied by it. Indeed, I argue that products aimed at narrow audiences, while not for everyone, tend to satisfy that minority that they're aimed at better than one-size-fits-all fare (think niche blogs or documentary films). And older products that still come up in recommendations are often those that have passed the test of time (classics).
When you look at a basic demand curve, the reasons why some things
sell less well than others are lost in the merged rankings. Popularity
is a multi-dimension thing: factors that determine an album's
rankings, for instance, can include not just the quality of the music
but also its genre, its release date, the fame and/or nationality of
the band, similarity to other artists and so on. But it's all lost in
the single dimension of a bestseller list, which obscures all that in a
mushed-together melange of apples and oranges. (You can read my earlier
rant about popularity lists here.)
following is a conceptual chart of the primary factor accounting for a
song's position pretty far down a demand curve. As you can see, looking
at popularity alone it's hard to tell whether something isn't very
popular because it's of narrow interest or because it's old (or any
combination thereof, although I've only shown those two for
If you tease apart those two dimensions, you'll get something like the following (again, the lines are just conceptual; different markets will exhibit different actual shapes):
Or, to put it another way, you can plot those two dimensions in quadrants like this (darker = more sales):
I'm still wrestling with how to visualize the actual topology of the surface connecting those two dimensions. I suspect it's kind of a spout shape, but without actual data I'm just guessing.
If you disregard quality, a rough equation of popularity might go like this:
Sales = Breadth of Appeal/Age
Breadth of Appeal goes from 100 (% of the population) to 0 and Age goes
from 1 to infinity. So if something is of broad appeal and brand new
that's 100/1 = sales factor 100. If it's niche and new that might be
10/1 = sales factor 10, which happens to be about as popular as
something of broad appeal but older (100/10 = 10). And so on. Totally
oversimplified, but it's a start.
Complicating matters, Kevin Kelly reminds me that "the fun thing, of course, is that narrow things can become broader as they age (Mississippi blues, which I would bet are more popular now then at their birth), or start broad when young and narrow as they age (opera)."
So there's lots here for the math geeks to chew on. Meanwhile, I'd love to hear any other ideas of better ways to visualize the many dimensions of popularity.