Not your screen monkey (he/him)
That is the Nielsen Ratings. One major difference is the Nielsens are a poll on a selected sample and is governed by the regular limitations of polls and statistical error. The data the streamers have isn’t a sample of a broader community - it‘s the entire community. So they don‘t have to infer whether or not viewers of Westworld also watched The Flight Attendant, they know exactly how many subscriber accounts did so. It’s still not perfect because they may not know why one show may appeal to a subscriber but not another, but they should theoretically be able to make data-driven decisions more effectively.Not challenging but curious - what makes you think cable TV hasn't been gathering and using this information for decades as well? They know what channels we watch when, and for those with DVRs they know what we record to watch. I can't see this as something new at all.
The other difference is the data collected by the streaming services is entirely private so there isn’t an independent outlet for any of it. They can release good news or suppress news of failure as they wish.