Nielsen to track Netflix viewers

What Nielsen's data shows, exactly, and how rigorously it is measured remains something of a mystery

In the five years since Netflix started streaming original series like the Emmy-winning House of Cards and Master of None, the shows have had a question hanging over them: How many people are watching?

Outside of Netflix, nobody knows the answer.

That’s because, much to the frustration of those in the industry who would like to have a firm idea of just how popular those shows are, the streaming services — Amazon and Hulu included — have been fiercely protective of their numbers.

Now, Nielsen, the 94-year-old company that for decades has had an effective monopoly on measuring television ratings in the United