In September 2012 registration requirement to ask questions has been introduced:
In the past 60 days, 76% of all questions from unregistered users have been either down-voted below 0, closed, deleted, or some combination of the three.
That's a total of 182 questions, compared to 877 similarly bad questions from registered users. It's a relatively small number, but as a percentage of the total it's high enough that implementing #1 holds little risk - at worst, you'll lose maybe a question a day from someone too lazy to register.
So, I've turn on the registration requirement in order to ask questions here. Let's check back in a month or so and see if it made any difference...
Now that more than 3 months passed, is it time to somehow see if it made a difference?
If I recall correctly, back then one of major concerns against this was that it may somehow inhibit asking good questions. With this in mind I think it would make sense to find out about the differences in the amount / rate of "good" questions (defined as say, open with non-negative score).
Given that registration presumably simplifies handling of question bans I think it would be particularly interesting to estimate if there was a difference in amount (rate) of such bans.
It would be also interesting to study the difference in "ban failure rate", which could be estimated as percentage of users caught at attempts to overcome it: those who created fake accounts that were later discovered and merged into original banned account.
- It looks quite simple how to get upper bound of detected attempts to abuse question ban. First, let's count how many accounts were added in last 4 months, as of Jan 12 these are roughly between 62044 and 78338,
78338-62044=16294. Now if we find how many of these accounts are gone, as indicated by respective user profile being
404 Not Found, this will give us how many accounts were either self-deleted, or gone through legitimate merges, or... and this is exactly what I'd want to estimate... or were merged as a result of detected abuse of question ban. It is of course impossible to manually scan 16K+ profile pages, wonder if this could be done somehow automagically?