[IanCal]

I think that's a disingenuous reading.

Nielsen ratings are for small subsets of users who explicitly opt in to tracking. That's not the same as "uniquely identify all end users of my website" it's like paying user testers.

[scarface74]

Nielsen tried it’s best to get a demographically representative sample of households. It wasn’t purely a self selected sample. I doubt people were incentivized by the $5 they put in envelopes.

[IanCal]

I didn't say self selected, I said opt in.