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Its ordered by the number of votes but the answer chosen by the user is shown first. In some of the questions, the chosen one may not be right or incomplete or not so good as a different one. Many new users may not scroll for the second one which might have more votes. The actual owner may not come back and select the new better answer. I think a good option would be to display the highly voted answer first, followed by the chosen answer and then the rest in the order of the votes. This way good answers are not missed.
In short, When the answers are sorted by votes, my suggestion is to put the chosen answer(by the owner of the question) in the second place than the first place.