In the Tor.com thread referenced in the previous Hugo post, Charlie Stross asks:
Leading off at a tangent: in light of the age profile of Hugo nominees/winners, has anyone done anything similar about SFWA and the Nebulas? What’s the average age of SFWA members, and what’s the average age of Hugo voters? Could the perceived loss of relevance of the Nebulas over the past decade possibly be a harbinger of the same trend — age-related conservativism — hitting the Hugos?
I don’t know of any available demographic data about the age of SFWA members or Hugo voters, but we do have the list of Nebula winners, courtesy once again of Nicholas Whyte. Here’s the graph for the Nebulas, done in the same way as for the Hugo graph in the previous post:
Doesn’t look much different, does it? The average age of a Nebula winner has risen from 37 in the 1960s, to 53 in the most recent decade, but the most telling data is the number of winners who were in their twenties and thirties per decade. In the 1980s, there were 27 winners in their twenties and thirties; in the past seven years, there have been four. And three of them were Kelly Link.
This age trend doesn’t hold for the Clarke or Tiptree award, both juried awards, but neither of them have been around for very long compared to the Hugos and Nebulas. Jeff suggests that we look at the Hugo nominees, to see if the nominees are younger and the older, familiar name always wins, and it might be interesting to look at the Locus award to see if the wider voting population makes a difference, but I think I am turning into crazy stats lady already and I will leave those for another day.
There’s more interesting discussion over at James Nicoll’s journal. If you want to do your own number-crunching, you can get the spreadsheet Niall and I used here.
vector-bsfa.com 
I’d be interested in seeing the equivalent chart for the Grammys, where rock-and-roll awards are now being won by 60-year-olds like Springsteen and the Stones.
The Grammys would be complicated by the fact that multiple people win quite often, though. What age should you assign to a band who wins an award? The mean of the band members’ ages? Or should you include all the band members separately as winners? And what about the Best Album award going to the O Brother, Where Art Thou? soundtrack in 2002?
The Nebulas are much more prone to log-rolling and various other systems gaming. One would need to somehow factor that in to an analysis. One could also of course check relative ages of those who make Year’s Best volumes. I’m guessing they would tend to be higher, since publishers demand a certain number of marketable names to put on the cover and marketable names will probably not be in their 20s or early 30s. It would be interesting if the average ages of writers were lower than the Hugos, though. Also, the winners of the World Fantasy Award would be interesting.