Criminal Minds

Criminal Minds has been consistent in the Nielsen ratings - making the top 20. The ratings for the week ending September 9 had CM at #13. The previous week’s rating was #10. But in all fairness, everyone was watching football (apparently. I HATE football! But pre-kick shows and games took the top four spots on the list).
This made me interested in the ratings themselves. I get a report each week from ENews (Seven -Daily Ratings Report). Here’s an excerpt:

Home and Away wins. Border Security and The Force match Nine + Ten in total audiences and dominate in key demographics. The Force peaks at 2.08 million and is Monday’s #1 programme for total viewers, 18-49s and 25-54s. City Homicide is up 79% on 1 vs 100 and wins in total viewers, 18-49s and 25-54s. Criminal Minds wins in total viewers and 25-54s.

I think this comes from Sydney, which is why I don’t recognize some of the shows or networks they talk about. But anyway, CM is the winnder in total viewers age 25-54. Right? City Homicide is up 79% - 79% of what I have no idea.
Anyway, this all made me more curious to see how Nielsen arrives at their ratings.

We collect information from approximately 25,000 metered households starting at about 3 a.m. each day, process approximately 10 million viewing minutes a day, and make more than 4,000 gigabytes of data available for customer access the next day. In addition, we collect and process data from 1.6 million handwritten paper diaries from households across the country during sweep periods.

They choose families based on geographic and demographic info. They get a cross-section of households. So the 25,000 people is like a mini U.S. They have the same ratios of education, income, age, rural vs. urban vs. suburban as the larger country. That way they can get an accurate picture of what different groups of people are watching.
They install equipment in the homes of families who choose to participate. This tracks what they watch, as well as the age and sex of the individual family members who are watching. They also use paper diaries to compile information. This helps networks, tv stations, and advertisers determine where to put their time and money.
This is also why shows that are sometimes popular with critics and not audiences get cancelled. It’s all about who’s watching.