Is the demographic profile of users of this board representative of the demogrpahic profile of the whole reef keeping population?
How bad would it be if you use this population and the real population is very different?
Personally I doubt this is a suitable way to measure the population - I would expect the age profile of this board, and in particulat people who respond to this thread, to be much younger than the age profile of the parent population. To what extent would be very hard (expensive / impossible) to estimate.
The ages given by people tend to support this.
You will have unusual geographic distrubtion problems too. Many (most / all) sales campaigns don't try to sell to the whole planet.
I'm 32 and in the actuarial profession (hence my thoughts on demographic problems with a measurement like this).
There is always one in the crowd that has to argue, hahah...
I was surprised to see so many "younger people" in the room. Of course its early and all the old people are still napping or taking their pills. I am sure they will stir after a bit...
I am 29, starting to push the envelope. One more year and I will start to be offended by the old jokes...