Nielsen makes you pay for it. In fact, that's really how they make their money, off prospective advertisers researching where the best "fit" is for their advertising dollars.
Nielsen will gladly release their numerical viewer data, but they won't release the more interesting demographic data, because that's their proprietary hook.
It must be powerful data too. As an example, while NCIS doubles or triples the number of viewers for Heroes, Heroes still commands a premium advertising rate, much larger than what NCIS can command. IOW, Heroes has far fewer viewers, but generates MUCH more money for NBC than NCIS does for CBS.
I got interested in this when CBS canceled "The Unit". I thought, why are they canceling a program that outperforms virtually every show on NBC. The answer was in the show's demographics and the ad rates it commanded.
Interesting. Thanx.
I imagine that the demo for Heros is the coveted younger one w/more disposable income. NCIS is, OTOH, likely older viewers and perhaps more conservative.
Frankly, we watch even less TV now than ever. Most of it is garbage and boring garbage, to boot. Also, we automatically reach for the mute when the commercials come on or we use that time to do something else. So much for the eyeball count, let alone the other demographics.
I suppose Nielsen has a detailed intake form that provides all the relevant data? I know statistics are more accurate than one could guess, but I always wonder just how much they have to crosscheck the intake data with other data in order to stay accurate. Data mining is a mature industry, and with the internet, it is probably fairly efficient, too.