That FOX so irritates liberals is reason for conservatives to lie to pollsters and tell them they're watching FOX continually even if they're not. Hey, liberals are required to lie so why should conservatives not be allowed the option?
That is not how TV ratings are done. they do not use polls.
To find out who is watching TV and what they are watching, the company gets around 5,000 households to agree to be a part of the
representative sample for the national ratings estimates. Nielsen's statistics show that 99 million households have TVs in the United States, so Nielsen's sample is not very large. The key, therefore, is to be sure the sample is representative. Then TVs, homes, programs, and people are measured in a variety of ways.
To find out what people are watching, meters installed in the selected sample of homes track when TV sets are on and what channels they are tuned to. A "black box," which is just a computer and modem, gathers and sends all this information to the company's central computer every night. Then by monitoring what is on TV at any given time, the company is able to keep track of how many people
watch which program.
Small boxes, placed near the TV sets of those in the national sample, measure who is watching by giving each member of the household a button to turn on and off to show when he or she begins and ends viewing. This information is also collected each night.
The national TV ratings largely rely on these meters. To ensure reasonably accurate results, the
company uses audits and quality checks and regularly compares the ratings it gets from different samples and measurement methods.
From Media Matters, the most "unbiased" source of news there is. 
