Anti-Recidivism System currently restricts recreated accounts to "posting only one question per week..."

I would like to understand why this rate was picked, and not, say, once a day or once a month?

The reason why I ask is that some users limited or banned at Stack Overflow attempt to circumvent this by posting at Programmers. I expect that learning more about the limitation would help me better understand its impact on Programmers.

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    I would guess that you have to start somewhere. Ask yourself the opposite: why not once a week?
    – slugster
    Commented Jun 26, 2014 at 11:54
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    @slugster that's possible, but I doubt it. Per my recollection of what SE team guys wrote about this system, they were planning to make it somehow... balanced, so that recovery from limitation would be difficult but still easier than hacking around to circumvent it. This makes me feel that they didn't just flipped a coin to decide on once a week :)
    – gnat
    Commented Jun 26, 2014 at 12:07
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    The tl;dr of my answer is - it was data driven, with a bit of a penalty tacked on, and the direction we're taking q-blocks in general so they mostly only affect those that can't be helped, while helping those that can.
    – user50049
    Commented Jun 26, 2014 at 12:33
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    I'm shocked that they're allowed to post anything. This is [attempted] ban evasion, pure and simple. Commented Jul 9, 2014 at 18:11
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    @LightnessRacesinOrbit I think the reasons are explained in the answer: "it's no longer easier to delete your account and try again than it is to try and get yourself established and asking better questions" (permanent bans seems to motivate users invent ways to circumvent these)
    – gnat
    Commented Jul 9, 2014 at 19:01
  • @gnat: Right, but if SE has figured out a way to identify duplicate accounts, why not simply block the new accounts from posting anything at all? Commented Jul 9, 2014 at 23:46
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    @LightnessRacesinOrbit then some (many) banned users would figure a way to create account that is harder to identify and keep bringing us headache (I saw first user who complained about the system already bragging how they could do that). Attack-vs-defense fight never ends. To me, new system seems to be matter of efficiency not fairness
    – gnat
    Commented Jul 10, 2014 at 5:55
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    @LightnessRacesinOrbit You can't identify a user in a way that can't be evaded. It's just simple like that, he can change anything that helps indentify him, unless you have a foolproof user behaviour interpreting algorithm that indentifies mouse movement, but even then, they could simply use the mouse. So in other words, "Life uh, ... finds a way" Commented Mar 7, 2017 at 11:09
  • @HopefullyHelpful: "if" Commented Mar 7, 2017 at 11:16
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    @LightnessRacesinOrbit I guess it encourages people to keep withhin the SE rules. Once you encourage them to create new accounts everytime they want to post, you encourage them to break all rules. Not to mention that the ban system is/was really sensible and isn't perfect. When creating new accounts becomes the path of least resistance you know you have a problem. Commented Mar 7, 2017 at 12:02

1 Answer 1


I explained it to a degree in the answer that I left here. I'm not certain if you realize how much depth your question has, and my apologies in advance for throwing a rather big wall of text as an answer to it.

It's important to clarify, we're improving question blocks substantially. There's some distinct groups of users that they affect, sorted by some interesting characteristics:

  • Those that tend to ask one or two questions per task they are given every day at work. Your classic help vamps.

  • Those that start off with several really awful questions, but would have improved had they had a shot at a few more. They can't go back and edit their previous posts because they're basically unsalvageable. These folks got off on the wrong foot, which isn't hard to do. We're quirky, what can I say?

  • Those that ask one or two 'meh' questions with the occasional really bad one, but only several questions per month. They end up being blocked, but it takes them a year because of the infrequency of their posts and low visibility - the system won't treat them as new users, but they essentially are. There aren't many of these, let's just call them the outliers.

The single worst offender when it comes to recidivism, or simply requesting deletion just to return with the exact same quality of questions is the first group, the ones that basically crowd source their job six days every week. Those are the users that we really want to slow down.

The second and third group aren't really hindered too much by the restriction, as they can generally start off with a decent enough question that it's lifted very quickly, or can write a few decent answers to help themselves out of it. However, those are also the groups of people that are more likely to just stop using the site due to the block than try and work around it.

So, we have one common denominator between all three groups. Due to the scale at which certain parts of the q-block system was designed, it's just too darn hard to get out of so folks either try and get around it, or just go somewhere else.

To get to your answer before I get down this rabbit hole even more, a week was chosen partly based on data (specifically, looking at medians when it comes to time lapsed between questions that didn't do very well) and a little penalty tacked on to make sure we get their attention. You could easily get the restriction lifted in a few days if you work at it, but it's no longer easier to delete your account and try again than it is to try and get yourself established and asking better questions.

Migrations are now blocked if they would put you over your quota on the target site, that just went out yesterday (and may not yet be in prod, but should be soon). Important to keep that in mind if you keep reading.

If all you wanted to know was 'why a week?' - stop here.

I'm putting something in front of the 'rougher' part of the question block system that's going to do something very similar to what the anti-recidivism limit does - it'll limit the amount of questions you can ask, based on your history, which is scoped through several different time lenses. It will start gently, perhaps limiting you to one or two a day, then a few each week, one per week, two per month and then Knuth help you because you really suck.

People that improve tend to ask fewer questions overall, and those questions tend to be much better received. Yes, we account for those times when you just have this outrageous project and need to ask more questions than usual, that's why we have several time lenses, and some other secret-sauce factoring in the works.

What does this get us?

People that treat questions as a resource that can be depleted, who learn how to ask questions only when they really need to and make them count when they do. Or, they keep throwing themselves at the wall and then get stuck in the mean hairy algorithm (Jeff wrote that, so it's intentionally both mean and hairy, I assure you - just the meanest hairiest tough-love you ever saw).

It's not yet done, but in the end, we're optimizing for giving the second group a fairer shot at showing us that they really get it and just got off on the wrong foot, and the third group a chance to either show up in the first or second group. The result should be, those that can be helped are helped, those that can't get stuck in the room with the big, mean hairy algorithm, and deleting your account no longer helps.

That, coupled with the spam layer that deals quite well with folks continuing to create new ID's trying to get around restrictions, should muffle quite a bit of noise. By the way, the spam system can also rate limit you ... oh yeah, they're gonna hate me by the time I'm done.


As of October 12th 2014, the rolling rate limits are now in place as part of the question-block system. This means, users will get more chances to write better contributions prior to being outright blocked. If you delete your account while being blocked or limited, you'll still be limited to one question per week.

While recent changes have given much greater incentive to create and build only a single account, there still must be something that makes deletion absolutely the worst option for those that hit limits or blocks.

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    OMFG I knew team put some thought into this system but I didn't realize how much. I particularly appreciate the overview of "time lenses" approach, things now make much better sense to me. Thorough explanation like this is exactly what I was hoping to get, thank you
    – gnat
    Commented Jun 26, 2014 at 12:46
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    What about people using Thor or ever-changing IP addresses? You have ways to handle them as well, when creating new accounts from different/untraceable IP addresses? (this applies both to help vampires and spammers) Commented Jun 26, 2014 at 12:52
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    You're more than welcome @gnat, in fact I'd been meaning to get more information about that out on meta. The scoping is something I'm excited about because it will do more to raise quality while giving us less of a reputation for having 'crazy restrictions' and such. The week also isn't set in stone yet - it'll be some time yet before I get enough data to look at it again. We have no history on accounts that trip this other than knowing they were previously blocked (hence, nothing yet to scope), so that's also part of the length we picked.
    – user50049
    Commented Jun 26, 2014 at 12:54
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    @ShadowWizard We do very well at dealing with that, kicking a troll that just cycles through exit nodes is now actually quite easy, and it's essentially the same pattern.
    – user50049
    Commented Jun 26, 2014 at 12:55
  • I see. I'd really appreciate if you also keep an eye on stats of attempts to circumvent limitations / ban by posting at other sites. I mean, asking at "outside" SE site hoping to get an answer or migration seems to be even easier trick than account deletion, how much of an issue it is now / can become with the newly introduced system
    – gnat
    Commented Jun 26, 2014 at 12:58
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    I'm asking because we still get daily spam from baba and diet products, for long long time and they seem to dodge all the filters somehow. Nothing fatal of course, just curious how they're doing it. Commented Jun 26, 2014 at 13:01
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    @ShadowWizard that's an exceptionally huge mobile network, and they use several of them, which is harder to get a fix on. Some of the changes we're making to the quality post-processors will likely also take care of baba, because baba seriously needs some taking care of.
    – user50049
    Commented Jun 26, 2014 at 13:04
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    Thanks, glad to hear that! Commented Jun 26, 2014 at 13:05
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    big, mean hairy algorithm - so that's the meaning behind your avatar.
    – Jamal
    Commented Jun 28, 2014 at 20:34
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    About your second group -- True newbies are not apt to have a lot to offer in terms of answers for weeks or months. Even if they're moderately experienced they will not have gotten a feel for the site and will be incredibly gunshy as a result of their almost inevitable pummeling on their first question. Expecting them to recover points through answers is expecting too much. I think those who come here with decades of experience do not fully appreciate the newbie situation. Commented Jul 18, 2014 at 19:55

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