I can tell you that its not a strong ocmparison to use Cognizant in any P/E valuation comparison. Cognizant (which i own many shares of and highly recommend but do your own research) is an outsourcing IT company. its no different than TATA or INFOSYS, except that it is growing much more rapidly than either (or Nielsen for that matter).
In the U.S. Nielsen is a monopoly, but in many of the emerging markets world it is not. Try looking at WPPGY, which by the way, owns the leading ratings company in China, CSM Media Research.
WPPGY owns much more than ratings businesses, but its been moving in the direction of ratings/research with strong acquisitions over the last decade.