The shows that make it to prime time tv are a select few. According to author Todd Gitlin, out of every 3,000 show ideas submitted to the networks each season, 100 go to script, and 25 get produced as pilots.
These shows are screened by people who are representative of the show's target audience. Screeners answer questions about which characters they liked, which ones they didn't like, and what they thought of the outcome of the story. The results are tabula ted and sent to network executives who make the final decisions.