What are the responsiblities of the 'executive producer'?
The executive producer, if that person is also a Show Runner, is in charge of every element of the TV show. It's like being the President of a corporation. Not only must that person deliver all of the stories, but you have to deliver every episode on time, complete, each week. This means you have to be on top of the budget and of the physical production as well as all casting and hiring. As executive producer, you're also where the buck stops on polishing scripts. If a show is not working, you need to figure out what to do to fix that. There are many show runners who are also show creators and find themselves writing or re-writing almost all the episodes.