I do not know much sql, but I tried at last some basic query.

Result is here:

data.stackexchange.com/mathoverflow/query/552109/…

I am not even sure whether it does what it is supposed to do.

I would expect to see bigger fluctuations on site with more questions, so I tried it on math.SE: data.stackexchange.com/math/query/552109/…

It is probably better only to show ratio in the graph, not numbers of questions.

This is the graph for math.SE: data.stackexchange.com/math/query/552118/…

This is the graph for MathOverflow: data.stackexchange.com/mathoverflow/query/552118/…

In both cases there is a drop before 276th day of the year, where it jumps up.

That should be October 3.

To be honest, I am not sure how to interpret those results. (And not even whether the query does what it is expected to do.)

I should probably leave this to some people with better SQL skills. (I would try a bit more if I had more spare time. There some work that should be done during the weekend.)

BTW I wanted to link to the question rather than to a comment above. All this was in connection with:

Perhaps this room might be a good place to ask for help - but it was frozen for inactivity two weeks ago:

It is probably better to take only whole years.

The numbers can be skewed because recent low quality question, which have been put on hold, without answer, and they are not yet deleted.

So I tried this:

data.stackexchange.com/mathoverflow/query/552123/…

Now at least there is no big jump around the date of data dump.

Probably it would be good to modify this to replace values for single days by one week averages.

However, I do not know how to do that.

Quite interesting, especially that the drop above is almost exactly one year ago. Is this maybe related? I wonder what happens if you run it with a different creation year.

@MartinSleziak in "the duplicate thread" it is explained how to find reviews. A way that is not mentioned is using /timeline which I think would contain completed reviews. Maybe we should add this but maybe there's a reason against it or it is not like this. Hence the question.

@quid Go ahead and edit. You can probably included linke to: How to see questions time line?.

I did not know that timeline shows reviews. SO I learned something news.

Thanks for the reply. I'll do so later. I notice it only very recently myself. It seems a newish feature (last spring).

@domotorp I guess that probably the safest choice is not to 2009 (since MO did not exists from the beginning fo 2013). And we also want to cut 2016 away. (We only want to use full years. We do not want the results to be skewed by recent posts - there are more recent posts without an answer than the general average.)

So this leads to these results and this graph.

As I said, it would probably be better to split this by week than have results for every single day.

And the same query for math.SE.

Still, the fact character of the graph changes close to the current date (it is more visible for math.SE) makes me suspicious that I am doing something wrong and that the query does not calculate what I wanted it to.

And even if it does, it is rather simplistic. Having at least one answer is not the same as being answered. (It should probably be restricted to answers with positive score. But that would definitely make the query more complicated.)

If I run it for StackOverflow, there is again a change near the current date. As I said, this look rather suspicious. But I am unable to spot where the mistake is.

Here is the same thing, showing numbers of questions rather than ratio: MathOverflow, Math.

And also StackOverflow.

However, whenever considering some statistics like this, I always recall the quote from the end of this answer.

"I don't feel like slicing the data by tags, time of day, day of week, month of year, phases of Moon, etc. The predictive power of this data is rather weak. The site is growing; its dynamics are different during school semesters and during holidays; some prolific answerers join, others quit or go on hiatus. Questions vary by difficulty and the level of specialization, which is something that tags do not capture. But if someone feels like slicing the data -- go ahead and fork the query."

"A question does not have to get lots of views to get answered: it needs to be seen by 1 person with the sufficient expertise, interest in the question, and time available. There is no way to predict when or if such a person will see the question. Choosing proper tags and informative title, writing a clear question in easy-to-read format, setting a bounty if needed -- all of these contribute to success more than pondering statistical tea leaves."

BTW as I mentioned in a comment, I think that adding statistics might be a reasonable thing to do. I guess that when somebody searches on meta for questions in this tag, then this belongs to the type of questions they are expecting to find.

Since we discussed mainly MO, I will copy the graphs for this site, here (from the last queries with restriction to dates between 2010-01-01 and 2016-01-01).