# We have a very large & widening gap between questions and answers. How do we fix it?

Cross-validated is a question-and-answer site. I think it's worthwhile to ask "How well does this website serve people who ask (on-topic, answerable) questions?"

To answer this question in a quantifiable way, we can look at the gap between the number of (non-closed) questions asked in a month in total and the number of (non-closed) questions with answers. I have a query that does this. Behold! The chasm between the number of questions asked in a month and the number of answered questions yawns!

This plot clearly shows that, since 2016, the gulf between questions and answers is more than 1000 unanswered questions per month. For 2018, it appears that the gulf may exceed 2000 unanswered questions per month.

If we amend my query to break out questions with the [tag:neural-networks] tag vs those without that tag, we can see that the answer gap does not solely arise from neural networks. (It was easier to just do the post-processing in R.)

Glen_b asked a related question several years ago, Are we seeing a dramatic drop in answers per question? But I think that this is not the best way to measure how we are doing. Instead, I think we should ask "If a user asks an on-topic, answerable question, will that user get an answer?" Additionally, I think we can decisively answer Glen_b's titular question in the affirmative (look at the plot!), since a bunch of smart statisticians have all made their own graphs and measured their own quantities of interest over the past several years. Now that we have evidence that there is a problem, I think we should start looking for solutions.

• I sometimes see mods comment on questions to the effect that they are unclear, but no close votes. Probably because mod votes are binding, and the mod didn't want to single-handedly close the question. It might make sense to ask SE that mods could also VTC in a non-binding way. – Stephan Kolassa Jul 6 '18 at 8:31
• Is this metric (fraction of answered questions) still as relevant as it used to be? Of all the value that's ultimately derived from our site, what fraction of that value is due to users actually posting a question and receiving an answer vs. just perusing existing, high-quality answers to common questions? If the latter is a strong and still growing majority, as I suspect it is, then how important is it really if a decreasing fraction of askers are receiving answers? – Jake Westfall Jul 6 '18 at 14:54
• @JakeWestfall If we take your reasoning to its logical conclusion, you seem to suggest that we could stop accepting new questions. – Sycorax Jul 6 '18 at 14:59
• Well, I think it's arguable whether that's the logical conclusion ;) In a world of unlimited volunteer time and expert knowledge, it would be good if we could answer all reasonable questions. In the real world, I think we should at least ask the question of how big a problem this really is, and not automatically take the issue as granted. What are the actual bad consequences of letting the fraction of unanswered questions continue to grow? – Jake Westfall Jul 6 '18 at 15:12
• I'm concerned about stats.SE remaining relevant as a place to have statistics and machine learning questions answered. If we gain a reputation as a self-serving backwater, where (new) users have no hope of having their questions answered, we'll lose visitors and users and become irrelevant. I don't want that to happen. I think that the Answer Gap provides some evidence that we are losing ground -- I think there are a number of good, solid unanswered questions which are relevant to modern statistics, especially in machine learning. We need people to answer them! – Sycorax Jul 6 '18 at 15:19
• I don't disagree. I just want us to think clearly and critically about what's realistically at stake so that we can set priorities accordingly. – Jake Westfall Jul 6 '18 at 15:22
• It is interesting to note that several other highly visited stackexchange sites, like 'super user', 'ask ubuntu', 'server fault', have the same issues with a growing gap between total questions and questions with answers. I myself believe that this is, in part, due to maturity of these topics/sites. The site stackexchange is largely based on activity around 'filling' the websites (scoring for good questions and answers). But what when originality runs out? We get stuck with a lot of visitors posting esoteric questions but not so much answers. Possibly we need a drastic shift to 'fight' this. – Sextus Empiricus Jul 9 '18 at 16:47
• One way or another the related problems in this thread are frequent topics on Meta. So, there is a lot of garbage here on CV. There is a lot of garbage on the internet and there's only so much one can do. It's more interesting and probably more useful for people who like CV a lot just to visit, answer what new questions you can, comment and vote a little, and then get back to the day job. Working on many poor old threads (downvoting, cleaning up, etc.) is as exciting as tidying up an untidy cupboard/closet when the alternative is watching one of your favourite movies or TV shows. – Nick Cox Jul 9 '18 at 18:40
• @MartijnWeterings only if we can also know which questions are worthwhile to answer in the absence of an answer being provided. – Sycorax Jul 9 '18 at 19:58
• @Sycorax, how many questions still get answered after a year? I guess we can easily remove them out of sight (sometimes the OP's never returned themselves) especially when we are dealing more often according Stephen Kolassa's suggestion of downvoting. Personally I am not a good downvoter but if there would be a clear 'old rubish' list I would be less reluctant. I actually tried to go trough the list of changes made by the 'community bot' which often bumps old posts, but the actions list by the user 'community' are full with minor edits like changes due to migrated questions and other issues. – Sextus Empiricus Jul 9 '18 at 20:11
• On stats.SE we have questions: 49,981, unanswered: 41,456 -- on physics.SE we have questions: 122,216, unanswered: 25,588 -- on math.SE we have questions: 968,501, unanswered: 218,115 --- If you want to find us on the All Sites - Unanswered Percentage (Sort) we rank #3 from last place. 😐 --- I make a point at looking at unanswered questions on sites where I frequent and trying to find something to answer from the list. – Rob Jul 9 '18 at 22:19
• @Rob Where did you take the first two numbers from? They are completely wrong. There are 127k Qs on CV and 50k unanswered. – amoeba Jul 10 '18 at 8:33
• @Rob There is ~50k unanswered questions and 120+k overall questions. Are you debating the 120k+ number? – amoeba Jul 10 '18 at 11:02
• @MartijnWeterings - Thanks. Regardless of those links, how about the last one mentioning 3rd place - room for improvement, that was the point to dwell on. – Rob Jul 10 '18 at 15:11
• I wonder, in the light of this thread... does AnswerCount also count answers with zero upvotes? Community already bumps questions with zero-vote answers now and then. I kind of wonder whether there should be more of this. (The problem being, of course, that it pushed new questions off the first page.) – Stephan Kolassa Jul 26 '18 at 8:24

There's no escaping that more answers to on-topic questions are required to close the gap.

More active participation in closure queues is a partial solution to our increasing volume of questions. However, a particularly distressing trend in this plot is that the number of answered questions per month is flat. Even if we more aggressively moderate poor questions and close duplicate questions, the plot in my post shows that the number of questions asked per month is linear in time, but the number of answers is basically the same. Moreover, even if we can identify more duplicates and close marginal and off-topic questions, that does nothing to address the fact that solid, on-topic questions often lack answers.

One of the major take-aways from Are we seeing a dramatic drop in answers per question? is that we need more "journeyman statistician" participation. I think this is a great idea, but I don't know how we get there!

• At the broadest level, Stack-exchange is undertaking to make the entire suite of websites a more accessible and friendlier place (discussed here We'd like your feedback on our new Code of Conduct!).

• Making SE more friendly seems like a good, long-term way to accumulate new users to answer questions to all sites. But is there anything that we, as statisticians and machine learners specifically, can do to gather more of our kind to answer questions?

# If someone answers a question in a comment, copy the comment in to an answer

I'm as guilty of leaving answers-as-comments as the next person, but if a question is fully and completely answered by a comment, you might as well leave that same text as an answer.

Moreover, if you see this happen, you can just copy-paste the comment to an answer, with attribution to the original commenter. I have a boilerplate explanation that I append whenever I do this.

 I've copied @____'s comment as an answer because the comment is, more or less, an answer to this question. We have a dramatic gap between answers and questions. At least part of the problem is that some questions are answered in comments: if comments which answered the question were answers instead, we would have fewer unanswered questions.



# Don't let the perfect be the enemy of the good

Sometimes we get a question which is completely answered with two or three trite sentences. "How do I know whether weight decay improves my neural network?" is fully and completely answered by pointing out that the question is an empirical one, and a good way to gather empirical information is by conducting an experiment. I'd like to emphasize that the question "How do I know whether weight decay improves my neural network?" is wholly on-topic, (it's about a core topic in neural networks!), so closing it is not the right solution. Instead of closing the question, write the (short, clear, obvious) answer.

Another question asked how to label images for a neural network. The poster had taken photographs of objects of interest and had seen code examples of data loading functions which yield image data and image labels. The user didn't know that, at some point in time, a human had undertaken the tedious effort of telling a computer "this image is a cat" and "this image is a car."

Both of these are on-topic questions with obvious answers. Not all answers need to be, or can be, multi-paragraph efforts with figures, citations, graphs and equations.

If you can completely answer a question with a few clear sentences, do it!

# More aggressively close overly broad, unclear and marginal questions

I think that a large portion of the problem is that there are quite a few poor questions, or marginally useful questions, or questions for which there is no known answer, or questions which ask the answerer to outline an entire statistical analysis project. We could do more to aggressively close these kinds of questions.

I specifically want to call out "marginal" as a genre of question. This is a question that asks a question that is, purely in the abstract, answerable. The dullest version of this question is "what's the best model for my data?" followed by a long explanation of how a database is configured, or how a website tracks user behavior. There surely is an answer -- but no one here is equipped to provide that answer without carrying out the actual analysis. This genre of question is the machine learning cousin to "What test should I run?"

Moreover, the strategy of writing a single, canonical answer to address a large audience of future readers is a losing proposition in the face of a rising tide of question for which the interest is entirely parochial. We need to close marginal questions.

As an aside, if anyone's looking for a quick way to get a lot of rep, we could use a canonical answer about back-propagation. I'm willing to award a princely bounty for such an answer (if I don't write one first). (Or, if one exists, we need to use that existing answer as a canonical duplicate target.)

(This seems to be a good place to note that I think we do a good job of directing questions which are purely about programming, math or obtaining data to their respective host sites, so good job team!)

# We have a "moderator blind spot" on modern machine learning; we need a specialist

I don't want this to sound like criticism or disparagement. We have an exceptionally knowledgable and experienced group of moderators. However, I think there is a "blind spot" among them with respect to modern machine learning topics such as , and . I've adopted these tags as pet projects of mine, but I do notice that VTC efforts often get stuck at 4 votes, rather than the required 5.

I think that stats.SE would benefit from adding at least one moderator who specializes in these topics. (But machine learning is a large field! We might need more than one!)

# Duplicate Patrol

Likewise, duplicate questions are a problem. It can be hard to passively identify and close duplicate questions without a near-omniscient knowledge of the thousands of question on CV. I often find that I can recall an answer to a question exists somewhere, but struggle to find the relevant thread.

To solve this, I've developed a strategy which I (lamely) call "duplicate patrol." It starts by looking at questions bearing some tag in which I am interested & feel that I am competent, and looking to identify "veins" of unanswered questions in need of an answer. If an answered version of that question can't be found, answering one of these question gives dupe targets for the others. When composing an answer, the goal is to identify common "themes" of questions, so as to address an issue which is of broad interest (and close several threads at once).

• +1. Regarding the "more sophisticated marginal question which is completely answered with two or three trite sentences": I'd say one should write those two or three trite questions. It will probably help the OP, and it might even help someone coming along later. Better than answering in the comments (as you point out at the bottom), or voting to close (with what reason? As you point out, such questions are on topic), or leaving unanswered. ... – Stephan Kolassa Jul 6 '18 at 8:02
• ... Yes, this may result in an increase of short answers. We would all prefer to write detailed, thoughtful answers crafted with love, but time doesn't grow on trees, and if we want to stem the tide, we will need to accept and embrace the Twitter-style answer. – Stephan Kolassa Jul 6 '18 at 8:03
• (+1) As a journeyman statistician myself, I'd say there's an annoying structural barrier to getting in new ones: as non-experts, we can mainly hope to answer recent questions (older ones that are simple enough for us to answer have already been addressed). But one can write an answer and then discover a few hours later that the question is flagged as a duplicate with a better answer elsewhere. Better search functionality or stronger filtering of 'first posts' might help. – mkt - Reinstate Monica Jul 6 '18 at 8:51
• Secondly, these answers to simple questions frequently get no upvotes because the questions don't attract attention - which is not very motivating. Possible solutions: 1) 'reviewing' and upvoting more answers, especially from new users (not just first posts). This need not be a formal review process, but something is informally encouraged. 2) more handholding of first-time posters encouraging them to upvote/accept helpful answers. And to follow the community rules. We should not have to spend so much time after they have posted to get them to do it well - the guidance should come before. – mkt - Reinstate Monica Jul 6 '18 at 9:04
• @mkt: for your point 1, note that "The Community user will bump non-negatively scored, open questions every hour that have at least one answer scoring 0 and none scoring more than that.", for your point 2, to be honest, I am skeptical that this would work. From what I see, new users won't even look through the help center or click on the many helpful links they see when composing a question. The focus on making SE easy to use also works against hand-holding. – Stephan Kolassa Jul 6 '18 at 9:19
• @Pere: There's certainly no requirement that the OP clearly state their problem in statistical language - indeed, when they don't know much Statistics, trying to do so often obfuscates rather than clarifies it - but they do need to state it clearly in some language. I've sometimes seen answers that retroactively clarify an unclear question to everyone's satisfaction; more often I've seen confusion, & some frustration, caused by answers that jump the gun. As you say, "the first step in any consulting work in any field is to find out what is the customer's problem", & ... – Scortchi - Reinstate Monica Jul 6 '18 at 10:40
• ... our mechanism for doing that is to place the question on hold & ask for clarification in comments. – Scortchi - Reinstate Monica Jul 6 '18 at 10:40
• (+1) I'd suggest appending the explanation - "I've copied this comment [...]" - as a comment to your answers, rather than as part of the answers themselves. Not that it makes much difference. – Scortchi - Reinstate Monica Jul 6 '18 at 11:47
• My two cents: 1) More and more questions coming to our site are in a sense obviously a good sign, as people still seem to feel it's worth their time to type a question. If we "succeed" to acquire a reputation that one is unlikely to get an answer from CV people may stop posting and the gap may close again. Would that be good? 2) There will always be a shortage of people willing to provide free labor (yes, my primary training was in economics :-) ). Short of talking universities and employers into offering tenure, promotion or bonusses for CV rep, only so much will ever change. – Christoph Hanck Jul 6 '18 at 15:01
• @ChristophHanck (1) I think you've missed the boat. The increasing volume of questions is not, itself, a problem -- the problem is the Answer Gap. (2) The fundamental blindspot of that variety of economic analysis is that it assumes that monetary reward is the only incentive that elicits participation. If this line of reasoning were correct, there would be exactly zero answers on CV. (Yes, my economic philosophy is heterodox.) We can reframe the question as "Since we can't bribe people, how do we encourage more volunteers?" – Sycorax Jul 6 '18 at 15:22
• Following up on the discussion above: It is true that upvotes motivate authors - especially those whose rep is between, say, 500-5000, I'd guess wildly - and it is true that it is unrealistic to expect that we can educate newbies to upvote a lot. That leaves experienced users - i.e., us - to upvote more. I try to do that, even when I feel that an answer may not be as good as it can be. As long as it is not false - roughly, as long as it is better than no answer - consider upvoting! That does not attract new authors to CV, but helps keep the ones we have motivated to continue answering. – Christoph Hanck Jul 7 '18 at 13:14
• @ChristophHanck Can you add that as an answer, I want to upvote it : ) – Matthew Drury Jul 9 '18 at 16:49
• Re: "VTC efforts often get stuck at 4 votes" (for machine learning questions). I rarely go through the VTC queue because 1) I have little time to answer questions now, and even less to go through the queue; 2) there isn't a way to filter the queue by tag. If I could choose to see only the machine learning questions (I mean, only the question voted to close belonging to a certain set of tags), I could probably help in closing more questions. I'll ask a related question here. – DeltaIV Jul 11 '18 at 8:39
• @DeltaIV: you can filter the VTC queue by tag. Open the queue, then click on "filter". – Stephan Kolassa Jul 11 '18 at 9:08
• Woah, even just filtering by the neural-networks gave me so many questions to check that I finished my close votes for the day. There are a lot of these questions which are of low quality and/or very old. – DeltaIV Jul 11 '18 at 9:59

# Downvote

Here is the mouseover text on the downvote button:

The question does not show any research effort; it is unclear or not useful

I'd recommend we be more liberal with actually clicking on that button. If a question is "not useful", downvote it! If someone else finds it "useful", they can always upvote it.

Why? This is why:

The system will automatically delete unlocked, unanswered questions that have negative score that are at least 30 days old.

Vegetation needs to be pruned so healthy growth can resume.

If you are concerned about the reputation loss from downvoting, remember that you get your rep back when the question is deleted.

The system will automatically delete unlocked, unanswered questions on main (non-meta) sites with score of zero (or one, if the owner is deleted), fewer than 1.5 views per day on average, and fewer than two comments that are at least 365 days old.

(So: if you find an unclear and un-upvoted question that already has one comment, e.g., a request for clarification, think twice before adding another comment. (Or: just downvote per above.))

• (+1) I think the admonition to offer helpful feedback to posters in the hope that they edit their question into something useful has become a bit of a millstone around the community's neck. It's a wonderful goal and kudos to those who do it. But it sucks up time that could be devoted to better questions, which get lost among the dreck. And the feedback is ignored too frequently for it to feel like a productive activity. – mkt - Reinstate Monica Jul 6 '18 at 8:31
• NB: There's no rep. cost for down-voting questions. – Scortchi - Reinstate Monica Jul 6 '18 at 8:47
• @mkt: You may have already read Stephan Kolassa's interesting post here. I think there's often a middle way between leaving no feedback beyond the boiler-plate & giving an exhaustive list of things to clarify that, as you say, may be completely or mostly ignored. An initial comment can be thought of as putting out feelers - if the OP's interested you can go into more detail. It can be fun, after all; but if it starts to feel like drawing teeth, just give up. – Scortchi - Reinstate Monica Jul 6 '18 at 11:00
• I've been active here for some time and didn't know that negative-score questions were pruned! Good point! – Sycorax Jul 6 '18 at 12:41
• I think one could clarify that the downvote can be used judiciously, more like a scalpel than a chainsaw. – Sycorax Jul 6 '18 at 15:34
• @JakeWestfall: I'm not sure if it's more satisfying to see your question linger on receiving no attention whatsoever, or to get a clear signal that it's not up to scratch. But it'd encourage answerers if the pool of unanswered questions were more a treasure trove & less a rubbish heap. Almost half of unanswered questions have neither up-votes nor down-votes - coming to a decision as to whether each should stay or not would seem sensible, to spare others the bother of having to paw through many poor ones before finding a good one. – Scortchi - Reinstate Monica Jul 6 '18 at 18:04
• Note also that serial down-voting (and up-voting!) is reversed by the SE robots when it is discovered, so we can't just go on a down-voting rampage to purge poor questions. – Sycorax Jul 6 '18 at 18:10
• @Sycorax: note that serial voting is only voting that happens to a single user. I don't think there are many users that post multiple questions that my proposed "treatment" would apply to. – Stephan Kolassa Jul 6 '18 at 18:25
• Oh, so you're saying if I downvote a large number of questions by different users, that won't be reversed? – Sycorax Jul 6 '18 at 18:27
• @Sycorax: AFAIK "serial downvoting" means giving several down-votes in succession to the same user's posts, & that's what the robots hunt. – Scortchi - Reinstate Monica Jul 6 '18 at 18:27
• @JakeWestfall: I don't think it's gaming the metric. SE does have reasons to remove downvoted and unanswered questions - namely, that they are noise, not signal. They run counter to SE's mission of providing a searchable repository of knowledge. Thus, they should be removed. And consequently not counted among unanswered questions. – Stephan Kolassa Jul 6 '18 at 18:27
• Serial voting explained at Meta.SE. – Stephan Kolassa Jul 6 '18 at 18:29
• @XavierBourretSicotte: sounds just like "not useful" to me. – Stephan Kolassa Jul 7 '18 at 18:07
• @DeltaIV: closed questions with zero or negative votes and without upvoted answers will also be auto-deleted. See point 7 in the list. – Stephan Kolassa Jul 10 '18 at 20:32
• @Rickyfox: I know that I for one have started writing more short answers per my comment. I'd rather write a short answer and have the OP come back with requests for clarification in a comment (which I will usually happily address), rather than write a long answer that gets little to no love. – Stephan Kolassa Jul 25 '18 at 12:21

We do not have a problem with unanswered questions. We have a problem with low quality questions.

See the below image from this sql script which gives for the monthly answers and questions the 10-log of the average score.

• The overall decline for both questions and answers makes somewhat sense, since it takes time to acquire votes. (It does make the voting system somewhat biased for older questions and answers, but I can not imagine that this is very problematic)
• The relative decline shows that the questions are now being less valued (relatively) than the answers (this is true for other stackexchange sites as well). This may indicate that the questions are becoming, on average, less good/valuable (at least in comparison to the average quality of the answers)

So I believe we should not try to work on getting more questions answered, but instead on getting a better fraction of good questions.

Sidenote: We see that answers are getting relatively higher scored than questions, but this is not necessarily due to 'a change in the questions' (although I believe it is a factor). It might also be caused by answers getting better.

A possible mechanism is a selection effect. The users of stackexchange are being trained (by the voting system) not to give answers when they are likely not gonna attract votes.

People answering questions are more influenced by the voting system than people asking questions. The result of the voting system, aiming for bounties and hot questions, is that less attractive questions are also less likely gonna get an answer. That low score, less popular, questions are not getting answers is (nearly) an intentional part of the stackexchange formula.

Total/Unanswered votes for questions above some score: It is interesting to check out this SQL script, which looks at total questions vs unanswered questions considering questions with some minimal score. For questions with a score 2 or higher the gap starts to become smaller and questions with a score 5 or higher are nearly always answered.

answer rates for questions above some score The graph from this script indicates an interesting drop in answer rate for questions with zero votes. Questions with $\geq0$ and $\geq1$ score have most of the time very similar answer rates except for a sudden shift in the last year where questions with $\geq0$ score have a particular low answer rate.

This shift is not something due to a change in the behavior, but the questions with 0 score and 0 answers get removed by community after one year.

Questions with score >1 Thus the drop in answer rate has always been there and is an effect of the community requiring time to answer questions or remove bad questions (and hence you will see that more recent questions have a worse answer rate).

You can see these bumps in all of the graphs so these "trends" should not been seen as solely a change in behavior. Some better way of looking at it would be to select only the posts with score>0, in which case you still see a gap, but it is not increasing a lot in time (the absolute numbers might be even decreasing).

• Unanswered questions with 0 votes and 0 comments are automatically deleted after 365 days. – amoeba Jul 12 '18 at 8:52

Most likely yes (currently ~60% of all questions are answered).

The question graph is biased because the unanswered question series assumes these are 'on-topic and answerable questions' which they are not. There are thousands of questions among that total which are duplicate, unclear, off topic, too broad, etc (i.e. questions that should already be closed).

I think there could be a rank of actions to be taken which consequently would make the next action in the rank easier to achieve.

1. Quickly/immediately closing questions is fundamental.

Let's set up the asking quality bar at an average high level. Let's use the SE system to our favour, not have it as an obstacle. One of the greatest advantages of SE in comparison to other types of 'forums' is that we don't need to answer the same and same types of questions again and again.

We need more users with the close vote privilege. Moreover, +3k rep users should not defer to immediately close questions which are duplicates, off-topic, unclear, broad, opinion-based. Even if the question is 'clear' to you, but someone requested clarifications in comments, if you judge the request is valid, then also vote to close it. Help the person who is seeking information to answer the question.

Let the following do their job:

• close reason notice messages;
• the tour and help center pages; and
• the many posts we have on Meta CV;

It is important we don't treat new users differently regarding this aspect. Everybody (who speaks English), if they want to, can improve their question with all the guidance currently available in the Stack Exchange network. A new [Ask Question Wizard] which will facilitate even more the task of asking is coming.

We don't need to be impolite to (new) users to carry on closing questions firmly. We need to give priority to build a high quality repository Q/A (which interests to coletivity) over the single user experience.

2. Vote.

Currently, we have ~23k answers with zero score (most of them has zero votes). We don't need more specialists to vote on many of these. Let's vote for them!!

Compare how such types of answers increased from a previous related post: Criterion for "Unanswered" question - should it change?.

Alright, I would then agree with Xavier and Sycorax.

If someone answers a question in a comment, copy the comment in to a community wiki answer.

Please, dO convert the comment into an answer, but do not make it community wiki. Give the proper credit to the commentator in the answer, but don't make it community wiki just because of that. Many reasons to do so:

• You are already doing the community a favour by answering the question. Answers should always be provided as answers (agree with this or not, it is how it works). If you take the time to expand an answer based on a comment (or even copy it from a comment), and that information is useful, you should share the credits for it. The community will benefit from more users having privileges which are based on reputation (voting, casting close/reopen privilege, accessing moderators tools, etc). Give the proper credit to the commentator in the answer, but do not make it CW.
• If you make it CW you are inviting anyone to edit/own that answer as well. Not always this is wanted, because it might happen someone will add content you don't agree, and by making it CW it is more difficult to make your own point to prevail.
• That is not how community wiki is supposed to work. It is not a quick fix.

I won't blame users who answer in comments (despite I don't encourage this). I've read some people arguing sometimes they don't have the time to write a full answer, so they make comments to help OP (fair point). In other situations, the answer is simple and people don't want to have in their answer history a simple answer (so, they just comment to help OP).

Because such users decided to comment, instead of posting an answer they don't have the right to complain if someone else decides later to convert their comment into answers and earn reputation from it. If someone gets upset with this, the solution is very easy, post the comment as an answer next time or just don't comment. I doubt most users would be upset about this, though.

Remember that converting a comment to an answer is not a zero cost activity. You need to read everything, post and format the answer, and sometimes expand it. The casual reputation is deserved.

• the cumulative answer rate is 60% but the instantaneous answer rate is declining more rapidly and currently is below 40% (data.stackexchange.com/stats/query/872406/…). (a part of the recently unanswered questions might become answered in the future) – Sextus Empiricus Jul 10 '18 at 15:34
• None of the arguments in the "CW is not a quick fix" thread pertain to using community wiki as a way to collect some other person's answer-as-comment into an answer. – Sycorax Jul 11 '18 at 13:01
• I linked to a stats.cv meta thread where the topic is discussed. – Sycorax Jul 11 '18 at 13:29
• I don't want to be seen as "stealing" someone's credit for rep. I have enough rep. All I want is to do is have answers in the right place. If people don't want to make it CW, that's their business. I'm not a cop (or even a mod!). – Sycorax Jul 11 '18 at 14:08

We need more answers, and therefore answer-writers There's no escaping that more answers to on-topic questions are required to close the gap.

In my opinion this is the single most important point, and all other ideas, while very good, will only have a marginal effect as they are not addressing the fundamental structural problem the site is facing. With that out of the way here are a few controversial ideas ranked from most impactful to least impactful in my opinion.

### 1) A paid, targeted advertising campaign

• At statistical conferences, in events, awards
• In specialized journals, magazines, books
• On related websites, forums

### 2) A free advertising campaign

• Links with non profit and teaching organizations
• Partnerships (e.g. with Khan academy, Datacamp or others)

### 3) A banner on the homepage

why note, Jimmy Wales does it all the time

### 7) Unofficial guerrilla campaign

• Ask the top 100 active users to promote an organized, unofficial guerrilla campaign on campus, at work, during conferences.
• Ask professors and TA to discuss SE and its usefulness with their students in class

### 8) New bonuses, badges and recognition awards for new users

You guys had it easy answering questions on the usefulness of $R^2$ back in 2011 and getting 250 votes for a 15 line answer ! Now days getting 1000 points is a battle.

Since SE is an educational and most importantly very useful website for students and professionals alike, I don't see why we shouldn't aim to attract new contributors in any way we can.

• .... as they are not addressing the fundamental structural problem the site is facing. I have to politely disagree. To me, the fundamental structural problem the site is facing is users with close vote privilege deferring to immediately close questions (specially from new users) and let the close reason messages and feedback provided from comments to do their job. We have thousands of low-quality/unclear questions which remains open for eternity (also, lots of duplicates not closed). We need more people moderating and acting quickly on poor questions. – Andre Silva Jul 7 '18 at 16:03
• The second problem to me is also about voting, but voting for answers. Currently, there are 23k answers with zero score (assume most of them are zero because of no votes). Are all these answers that bad? – Andre Silva Jul 7 '18 at 16:06
• From experience, the more academic a SE site gets or the higher its level, the harder is to get an answer upvoted. Cross Validated is in the same path as Physics SE or Law SE, where it's actually hard to get a handful of votes. In Wordbuilding, Skeptics or Academia SE you can get a lot more votes for the same effort. Probably, that has an impact on motivation. – Pere Jul 9 '18 at 22:09
• Asking professors to discuss SE and its usefulness to students will add more questions, not answers. If you want more good answers, we need to communicate the value of SE and its usefulness to other statisticians/academics. – Ben - Reinstate Monica Jul 17 '18 at 9:11

I don't think the problem is solvable just by closing more questions or downvoting. I think all users start at a point where they just ask questions, then some of them become knowledgeable enough to start answering questions, and get hooked in the process, so the number of answers/time increases. Then, as in all human endeavours, they reach a point where they start losing interest and/or they have less time to spend in this activity, thus the rate of answers decreases (save for a few exceptions). Since new askers keep coming, but just a fraction of the askers become answerers, I think the only solution is to find a way to increase the number of answerers (maybe encourage short answers, by upvoting them) or to just accept that the gap will increase.

As Nick Cox correctly noted when commenting on the OP, "[..](downvoting, cleaning up, etc.) is as exciting as tidying up an untidy cupboard/closet when the alternative is watching one of your favourite movies or TV shows". Thus if we can't manage to increase the number of answerers, a fortiori I don't think we can manage to increase the number of downvoters/closers/etc. It's true that the last two activities take less time than writing good answers, but it's also true that they're harder to pitch to users.

Another possibility is that the gap is mostly due to an increase in low quality questions: Martijn Weterings' answer provides (now stronger) evidence in that sense. However, given that it takes little time to write crappy questions, and that there is a surge of interest for some topics related to Statistics & Machine Learning currently, I don't think the rate of crappy questions will go down easily.

UPDATE: with this query I retrieved the number of total & unanswered questions per month, for each of the 10 tags with more unanswered questions (today).

The result suggests that r, regression, machine-learning and time-series are the main drivers behind the growing chasm. Thus, concentrating the VTC & "recruit new answerers" efforts on questions with one or more of these tags should provide the most benefits. I remain skeptical of a sustained solution, i.e., I predict that answerers/closers will get bored of engaging in these endeavours soon before the question rate will drop. But let's see...