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1.
A passing observation: what proportion of users have reputation which is an odd number? OK, trick question: most users have reputation = 1. So throw them away: now what proportion of users have reputation which is an odd number?
2.

A fair bit over 1/2, I would guess. The only activities that I know of that gives you an odd number of reputation points are voting down (not being voted down) and getting an answer accepted. So among established users who have done both for a while, the proportion should be close to 1/2. The newbies will all have odd reputation.

3.
Aah that explains it! I thought that being voted down would give you -1 but in fact does it give you -10? Yes so that's what's going on. You get a gazillion people with 3 rep and then a gazillion people with 5 and etc etc. Thanks Harald.
4.
No, being voted down gives you -2, while voting someone else down gives you -1.
5.

From a quick look at the data, Harald's conjecture seems correct. (I think it's most obvious for reputations between about 50 and 100.)

Also, at very low reputations there seem to be effects mod 10: 21 is much more common than 19 or 23, 11 is much more common than 9 or 13.

• CommentAuthorHarry Gindi
• CommentTimeMar 25th 2010 edited

If your reputation never passes over 100, you cannot have even reputation, which is why Harald's answer is obviously correct.
6.
7.
Okay, I'll admit that it's possible, but how many users came here and have posted only a few answers and had an odd number of them accepted?
8.

So what is the easiest way to have reputation 2? Getting an answer accepted, with seven downvotes and no upvotes? Well, nobody has reputation 2 so far.

9.

Another way is to post an answer as a new user (you have 1 rep), somebody votes you down (still 1 rep), but then takes back their downvote (brings up to 3 rep). Then your answer wins a 100 point bounty (bringing you up to 103), you cast a downvote (down to 102), and get a post repeatedly flagged as spam, so it is automatically deleted an you're penalized 100 rep.

10.
A 100 point bounty on a community wiki question.
11.

Wait, taking back a downvote increases the reputation of a 1-rep user? That doesn't seem like the intended behavior.

• CommentAuthorHarry Gindi
• CommentTimeMar 25th 2010 edited

Yep.

I wonder if we all got together and voted a person with 1 rep down, then removed all of the votes at once what would happen. Would the system see that as reputation gained? Could you get past the 200 rep limit? Quick, let's get a hundred people in on this!
12.
@fpqc: "If your reputation never passes over 100, you cannot have even reputation". This is surely false. The reason I made the original comment was that I was browsing through the users pages. From page 44:

http://mathoverflow.net/users?page=44

up to the last page (110 as I write) everyone has 1 rep. And then there's a jump to 3, and then to 5, etc etc. But someone has 10: check out

http://mathoverflow.net/users?page=41

sandwiched between all the 9s and 11s, and this guy has completely minimal activity. So what you write is surely wrong.
13.
@Buzzard, but how did he get ANY reputation? He has asked no questions, provided no answers. Is there any other way to get reputation?
14.

A bit more "seriously" (but not too seriously, hence the quotes): do MO reputations follow a power law, like John D. Cook says SO reputations do? (Yes, this is the same John D. Cook that is on MO.)

• CommentAuthorHarry Gindi
• CommentTimeMar 26th 2010 edited

Oh yes, I admitted that was wrong a while ago. Anyway it is almost impossible that it will happen, given the way the software is designed.
15.

but how did he get ANY reputation? He has asked no questions, provided no answers. Is there any other way to get reputation?

That's a pretty good puzzle. This user posted an answer to an elementary homework-ish question that didn't belong on MO. The answer was accepted and got three downvotes before it was deleted by a moderator (which is the only way an accepted answer can get deleted). Technically the user "should have" reputation 1 since the post that earned the reputation no longer exists, and that's what it would come out to if a moderator triggered a reputation recalc on this user's account, but I'm not going to because it would be a shame to lose our only rep 10 user.

A bit more "seriously" (but not too seriously, hence the quotes): do MO reputations follow a power law

You can grab the database dump and run this command in a terminal to get a sorted list of reputations: `awk -F '"' '{print \$4}' users.xml | sort -n`

16.
I'm not sure exactly how it was done, except that bounties were involved, but there now is a rep 2 user. At this moment it can be seen here:

http://mathoverflow.net/users?page=48
17.

@Jonas: looking at that user's reputation history graph, it appears he spent almost all his reputation on bounties. Not so long ago, he had something like 1700 reputation.

18.
What caught my attention was that a bounty was posted and awarded for an old answered question by a familiar user, and I was surprised to see that the user's rep was 1. Then a couple of minutes later, the rep was 2. My guess: a downvote was made and then removed for the novelty of having 2 rep. Which is why I posted in this thread, where scenarios for achieving 2 rep were mentioned.
• CommentAuthorHarry Gindi
• CommentTimeApr 21st 2010 edited

Yes, I think maybe he's trying to make a point that reputation does not matter to him or something? I really feel like we should discourage this sort of thing. I realize that Brian Conrad is doing it for a reason, but if people are really going to answer in comments to make a point, it just makes life a lot harder. Perhaps somebody could do something like turn off reputation/voting for people who are against it in principle, but what is currently being done is really irritating.

19.
Harry, I disagree. I don't see any problem with awarding bounties. The comment about BCnrd is really off-topic.
20.

No, it's not. Please check Leonid's history. He has purposely drained his reputation and made all of his old posts community wiki. Since then, he has left all of his answers as comments. It is absolutely on topic.

• CommentAuthorJonas Meyer
• CommentTimeApr 21st 2010 edited

I'm sorry, I was wrong. I didn't know about Leonid's switch to answering in comments, but based on your post I might have guessed. I don't mean to be argumentative. I'll just say that it seems like a fairly isolated phenomenon, and we can use RSS feeds to follow interesting commenters.

The point of my original post was frivolous revelry in having a rep 2 user, which seems to fit with the topic of this thread. But the method is also interesting. Unaccepted answers were deleted--this would prevent rep from changing until it is recalculated.
• CommentAuthorfedja
• CommentTimeApr 24th 2010

I also wonder what made Leonid to get rid of all his reputation points (I was quite surprised by suddenly getting a 500 point bounty from him for an old answer, which, ironically, actually was just an echo of his answer to my question on AoPS). Maybe getting exactly 2 points seemed very cute to him. On the other hand, I find it rather amusing to see the BanAnaMan quote getting 35 upvotes and a full proof of a not completely trivial statement on the same page getting just 1 upvote. What is just amusing me could irritate him to the extent of dumping all his points, but it is just a wild guess. We should ask him directly if we want to know the answer.

Answering in comments is an interesting idea though. To squeeze a proof into 600 symbols without making it incomprehensible is quite a challenge. I should try it some day :-).
21.

@fedja: I am a big fan of your answers, please don't put them in comments. Reading answers in comments on MO is like going to a fancy restaurant and have your dinner delivered in aluminum foil. Occasionally, and if the cook is Brian Conrad, it might be OK, but I hope it won't become a trend (-:

• CommentAuthorRegenbogen
• CommentTimeApr 24th 2010

After you lose your reputation in such ways, do your powers go away? Such as, ability to retag, etc..

• CommentAuthorHarry Gindi
• CommentTimeApr 24th 2010 edited

Yes, they do.

Edit: I missed Hailong's post, but

Hailong: +1

22.

Hailong: +1

23.

Hailong: +1

• CommentAuthorMariano
• CommentTimeApr 25th 2010

In fact, I propose that up-voted comments give more reputation than regular answers.... Or, rather, I prps tht up-vtd cmmts gv + rep than reg ans.

• CommentAuthorHarry Gindi
• CommentTimeApr 25th 2010 edited

I dunno, do I really deserve any points for posting a picture of a funky robot on Porton's question? I mean, yes, it was humorous and in good taste, but I wouldn't go as far as suggesting that I deserved points for it, let alone more points than a real answer. =p