https://www.metv.com/stories/david-ogden-stiers-was-hungry-for-acting-opportunities-while-on-hiatus-from-m-a-s-h

"Shakespeare, of course, is what I enjoy doing most," said the actor.

David Ogden Stiers said that he was often approached by doctors who assumed he had a medical background (https://www.metv.com/stories/david-ogden-stiers-said-that-he-was-often-approached-by-doctors-who-assumed-he-had-a-medical-background)

Though Stiers played a doctor, he had little real-life medical knowledge.