http://www.huffingtonpost.com/2013/05/22/star-wars-prequels-return-of-the-jedi_n_3313793.html

Here Lucas explains before Return of the Jedi how Yoda isn't a "real" Jedi. Yoda was never supposed to fight, instead he was a guru. Making Jedi Knights only one aspect of the Order is a good idea in my opinion. However, it would seem we need a new designation for the Jedi religion, if the Jedi are only the militarized crusaders. Perhaps Disciples of the Force, or something. I don't know. Order of the Force? Perhaps it doesn't need a name. I guess Jedi is a good name, as Yoda was referred to by Obi-wan as a Jedi Master. I just want the Jedi Order to not be all in one building on Coruscant. Yoda should always have lived on Dagobah, and be one of the less well known of the Jedi. That way he is simply never found in the Jedi Purge, for Obi-wan never told Anakin where to find him. It could be that Obi-wan trained Anakin without Yoda's approval, and so he didn't want Anakin ever seeking out Yoda and blowing his cover.

One other point: Jedi should be rare, even in the Prequels. I think that the assumption in the prequels should be that only humans use the Force, so that Luke (and the audience) would not expect a little alien dude to be a Jedi Master, like it was originally intended.