Television ratings are a very inexact science. Radio ratings, too, but this is about Monday's CFL matchup between the Toronto Argonauts and Hamilton Ti-Cats. It was the Labour Day Classic, so you knew many across this country would be tuning in.
A small collective of unknown people across this country carry PPM devices to record what they watch. Then, this number is extrapolated to estimate the number of viewers in total. It's like polling, and seems to discount streamers and such. Like I said, it's a very inexact science.
I follow Steve Simmons on Twitter, and saw this tweet from him.