Recently, my drama class has been talking about documentary theatre.  We were talking about if the stories should be true.  I started to think about subjects that would need true stories verses others that didn't.  What effect would the play have if the stories weren't true?

I have been thinking that if the play wants to make a statement then the stories should be true.  If the play is trying to make a point, and the stories aren't true, would it have any effect on the audience?  Would it take to heart like real stories would?  Or does the audience see it as just a play?