Okay, there's more data than I thought. =)

I've been through the Empire quotes, and have developed some hypotheses. I'll share what I have with you guys now, and see how the data matches up with what I have so far.

Current hypothesis: Yoda is a non-native speaker of English. He frequently makes errors natural for NNSoE. Often he inverts his word order to OSV, which, while VERY uncommon in the languages of Earth, is possible. It is almost universally dispreferred to put O before S, but some very few languages in South America do it, and marked forms of some other languages (like Mandarin) do it. Presumably, Yoda's native tongue (is there a name for this yet? If not, I may call it "Yodish", or perhaps "Dagobarista") has an OSV word order, and he is accidentally code-switching.

Perhaps in the prequels he has worse English because in between the trilogies he attended an ESL class. It does stand to reason that his English would improve given time, although in 900 years he should have probably been indistinguishable from a native speaker.

Some places where Yoda makes frequent errors:

Temporal adverbs—are placed sentence-initial, sentence-medial, sentence final, and in their proper place.

Auxiliary verbs – Placed inconsistently or left out (especially with “do”)

Negatives placed word finally -- this is okay in archaic English, as in “size matters not”

Equative clauses are almost always structured OVS (with O being the predicate complement)

Possible hypothesis for future study -- Is Yoda employing topic and focus (as per Halliday, see http://en.wikipedia.org/wiki/Topic%E2%80%93comment for a primer)

Next time, I'll tackle ROTJ and see if Yoda is consistent in his diction across movies in the same trilogy. Thirdly, we can take a look at the prequels and see what's changed, and perhaps amend our guesses.

Regards,

Tim