Asked here per advice at MSE.
For your convenience, data referred above is also quoted here (voting on deleted posts is included). Note this data doesn't take into account whether question was in the hot list:
Defining "outsider votes" as votes cast by someone who hasn't yet earned even 15 reputation on the site at the time the vote was cast
And looking at all votes cast during the past 180 days
We'll define "outsider agreement" as a case where outsider votes on a post are > 0 and insider (folks who've earned >= 15 rep on the site) upvotes - insider downvotes are also > 0
We'll define "outsider disagreement" as a case where outsider votes on a post are > 0 and insider votes are < 0
Cases of outsider agreement: 2,680
Cases of outsider disagreement: 277
Cases where the insiders' votes would've brought a post's score < 0, but outsider votes were present in sufficient quantity to make the post's score positive: 147
Total posts voted on by outsiders in the past 180 days: 3870
Total posts voted on by insiders in the past 180 days: 7186
Total posts voted on by both groups in the past 180 days: 3053
Q: What is the difference between outsider disagreement (277) and insider negative but for outside votes (147)?
A: So... Imagine you & I see an answer & we both downvote it. It's at -2. Then 3 people come in with nothing but the association bonus and up-vote it. It's at +1. There are 147 cases like that
Now imagine @enderland and @RhysW both downvote the same answer, so it's at -1 again. There are 277 cases like that.
Total insider votes during the past 180 days: 29,479
Total outsider votes during the past 180 days: 12,837
Q: am I reading this right -- there were ~700 posts that only outsiders voted on (insiders didn't)?
A: something like that
I'm not breaking this down any further right now, but a really common case for that involves answers to questions being upvoted by the asker
Q: Ok, so if I'm reading all this right, we have significant "outside" participation, but only in 5-10% of cases does that participation disagree with the community.
A: Right. And if you consider that even most of those 5-10% are "controversial" in the sense that they're getting both up-votes and down-votes from insiders, you can see there's a lot to be gained from community education.