Here’s a quote from The Wrap on TV from May 26, 2011:

(The Wrap is an industry e-magazine.) 

“Most of the broadcast networks are adding more sitcoms both in the fall and for mid-season. Is that a good strategy for drawing more viewers and a good one from an advertiser viewpoint?

Billie Gold (vice president and director of programming research at media agency Carat): Comedies, if they hit, can be very profitable for the networks, especially on the back end of syndication. The problem is that most freshman comedies fail unless slotted in a protected time period. So advertisers are taking a bit more of a risk if they are making long-term commitments or sponsorship deals in comedies.

Brad Adgate (senior vice president of research, Horizon Media): I think it’s a good strategy. Comedies have had a mild resurgence of late led by ABC’s "Modern Family." If you rank the highest-rated shows among Adults 18-49, there are now a number of comedies in the Top 15. From a business standpoint, it makes a lot of sense since comedies repeat better than dramas. So there is a more lucrative aftermarket and it typically brings in younger viewers, a consideration as the median age continues to rise at the four largest broadcast networks.

Sam Armando (senior vice president, director at media agency Starcom): People do not watch "Modern Family" because it is a sitcom; they watch it because it’s funny. Good content will draw more viewers to a program, regardless of its genre. 

Steve Sternberg (longtime head of research at media agency Magna, now head of his own research consulting firm and author of The Sternberg Report): I think scheduling more comedy is a great idea. It’s good counter-programming, and it will help the networks get a bit younger. The problem is that they seem to want to schedule them opposite one another. Also, the nets need to understand that family comedies work better than romantic comedies. Let’s keep in mind that three-quarters of all homes only have one TV turned on during primetime. Families are looking for shows they can watch together.”

Here’s a link to the entire article: 

http://www.thewrap.com/tv/article/fall-tv-questions-can-terra-nova-succeed-can-ashton-these-and-thers-answered-27672