An anonymous reader writes: Viewership numbers are vital within the TV industry. For years, the networks have relied upon ratings to make money — higher numbers mean higher ad revenue. The most important part of the ratings system is that individual networks can't just claim whatever viewership they want; third-party companies like Nielsen control the stats. But Netflix doesn't operate by the same rulebook, and this is frustrating the networks. Execs from Netflix and various networks have started arguing about it, both at an industry event this weekend, and in media interviews. NBC had hired a firm to estimate Netflix's viewership numbers, because Netflix won't release them. Netflix says the estimate is laughably wrong, but has also suggested shows fare better on their platform than on cable or broadcast television. If true, it gives them leverage to recruit more and better talent to produce such shows. But it's impossible to refute without numbers, and the networks are increasingly annoyed they can't do that. NBC thinks the media tends to give Netflix a pass on these statements. FX chief John Landgraf said, "[Netflix's Ted Sarandos] shouldn't say something is successful in quantitative terms unless you're willing to provide data and a methodology behind those statements. You can't have it both ways."