Nielsen says it will start measuring Netflix, Amazon

One of the mysteries of streaming services will now be known: how many people are watching online shows like Netflix's "Stranger Things"?

The Nielsen company said Wednesday it is introducing a new service that counts viewership of programming on services like Netflix and Amazon the same way that it does for CBS and CNN. Previously, only the streaming services had access to this information and, with rare exceptions, they didn't share it publicly.

Advertisers are eager to know this and so are television competitors, to have a sense of which streamed programming is successful and which ideas are falling flat. It's also likely the figures will be closely watched by analysts and investors in Netflix (NFLX), Amazon (AMZN) and other companies involved in streamed programming, especially as many ramp up investment in original programming. 

Netflix plans to invest as much as $8 billion next year on original content, the company said in a shareholder letter earlier this month

Nielsen says the public will be surprised to learn how quickly the streaming services have caught on.

The data will be collected from Nielsen's household panels, which includes 44,000 homes, and take as long as three weeks ot process, according to AdWeek