The Great Vote Count Analysis (Pre-Discussion)

[callforjudgement]

Your significance test doesn't work because it doesn't take into account the fact that each post is made by a player, and different players have different posting styles. As an extreme example, assume you have one hyperposter in each game who posts all the posts, and the other players don't post at all. Now what the test is measuring is the proportion of time the hyperposter happened to be scum. Your average is still correct, but your standard deviation isn't, because the number of samples is much smaller than the number of posts.

In order to work out if this is statistically significant, we need a workable null hypothesis, and "each post is equally likely to be made by each player, regardless of alignment" (what you have in your post) isn't it; even if there's no connection between posting frequency and alignment, we could still expect there to be a connection between posting frequency and player slot. I'm not sure offhand what the correct null hypothesis is, which is why I can't run the test myself.