[OldDeckHand]

'I’ve never understood exactly how they know how many people are watching a show"

They (usually the Nielsen company) have monitoring devices installed in a certain number of homes. They measure what those homes are watching relative to what the other monitored homes are watching - assuming they've sampled the right "mix" of people, they can fairly accurately extrapolate from those measurements what the wider American audiences are watching.

[The KG9 Kid]

... Or, the cable providers can just provide the information on what everyone is watching.

[Sacajaweau]

It's the WHY were they watching...

I watch him 'cuz I think he's a jerk....so a lot of people (like me) watching isn't necessarily a good thing. Gee...I missed him on the view...will I survive??

I DON'T WATCH THE VIEW.

[Graybeard58]

They (usually the Nielsen company) have monitoring devices installed in a certain number of homes.

Do you personally know a "Nielsen Family"?

I don't.