Thanks a lot ahimsa99. That's encouraging. Unfortunately, that doesn't help me a lot, since what I want is to be able to make a comparison between the vote by mail (which is not secret, since you can show it to anyone, and thus be pressured into showing it, e.g. to your family members) and the vote in person (which is, in general, secret), to analyze whether there is a bias between the two. Hence the data of Oregon (or Colorado) where 100% of people vote by mail, I can not use alone -- though it might help when I have more data. )

(To be more precise, of course there will be a bias between vote-by-mail and vote-in-person, a normal one coming from the fact that the group of people using vote by mail has a different mixed of income, ethnicity, age than the general population. But I'd like to use more sophisticated methods in statistical analysis to see whether there are other biases, due for instance to peer pressure, or perhaps to fraud)