The data, which covers the time period from June 17 to June 19, is somewhat surprising because previous estimates of Netflix viewership done by other entities have been refuted by the streaming service, which has long kept its tallies secret. Major networks have frequently questioned Netflix's actual viewership -- wondering aloud if the service is as much of a challenger to traditional TV as analysts (and the public) have asserted. The research is part of a larger partnership between Nielsen and TV studios that choose to opt-in to track viewership across streaming platforms such as Netflix, Amazon and Hulu.