Good list, bad list

Question

The Stack Exchange model does not work well for "big list" questions, and these are banned network-wide for good reason. However, many of the other Stack Exchange sites allow or even encourage list questions that do not fall under the "big list" category.

On the other hand, Physics.SE currently has a de facto policy against list questions of any kind, even if they are quite limited in scope and technical in nature. I know I'm not the only user who finds this frustrating, and so I would like to open this policy up for discussion. In particular, I would like to propose that we make a distinction between unhelpful "big list" questions and more productive "good list" questions that should be allowed on the site.

A good starting point for this is the "good subjective, bad subjective" post on the Stack Exchange blog. Although it doesn't mention lists specifically, it makes the helpful point that subjectivity in itself does not make a question unsuitable for the Stack Exchange model, and if a subjective question follows an appropriate set of guidelines then it can be productive. I believe the same to be true of list questions. In fact many of the guidelines for subjective questions in general could be carried over to list questions in particular.

The "good subjective, bad subjective" blog post gives the following set of guidelines for subjective posts. I think this will need some modification beyond just replacing "subjective" with "list", but it gives us a start in coming up with a suitable set of guidelines for list questions.

1. Great subjective questions inspire answers that explain “why” and “how” 2. Great subjective questions tend to have long, not short, answers 3. Great subjective questions have a constructive, fair, and impartial tone 4. Great subjective questions invite sharing experiences over opinions 5. Great subjective questions insist that opinion be backed up with facts and references 6. Great subjective questions are more than just mindless social fun

For list questions on physics, I think the most important requirements should be that they are based on facts and not opinions, and that they be sufficiently limited in scope, i.e., not likely to produce and endless string of answers, none of which is any better than the others. Of course, the latter is a judgement call, and we need to discuss the criteria used to make it.

Good list questions could include (for example) lists of applications of a particular theory; references to support a particular claim; or ways to determine a particular empirical quantity. In each case we have to be careful about scope ("What are some applications of Newton's second law?" would be a bad list question), but appropriately restrictive list questions of these kinds could be a useful and productive thing to have on the site.

I would be very grateful if anyone would like to update this question with some links to examples. Here is a recent one that sparked some discussion, but I know there have been many other good examples over the years.

Answer 1

Since my comment may have been part of sparking this I should probably say a few more words.

I am sympathetic to the position that carefully limited, actively curated, reasonably objective list questions can be a good thing (tm) for the site. I really am. But I don't believe that those conditions can be reliably met and I know from bitter experience that allowing list questions to proliferate pollutes a good Q&A.

So my opinion---personal not speaking ex cathedra here---is to shut them all down with extreme prejudice. Kill them with fire kind of thing.

None-the-less I will stand by a community decision--like I did during the period when books was on-topic.

But let me register my pleas that if you will have these

• that limits be set and enforced that keep us from having an endless procession of make-a-list-like-that-other-list-question-but-with-one-more-adjective-or-restriction questions
• that subjective ideas like "important" be kicked to the side of the road (and yes this means kill that stupid important-plasma-problems-not-including-the-most-important-plasma-problem question not just with fire, but with bolt after bold of highly ionized gas)
• that we not accept every list question that someone who has read a couple of pop-sci books can think up, nor even those that will occur to an average undergrad: those things are very well covered in endless books and will be treated in any course of study

So there you have my list of fun-hating conditions, and now you can all get off my lawn.

Answer 2

See also: Why are "shopping list" questions bad?, http://blog.stackoverflow.com/2011/08/the-future-of-community-wiki/

TL;DR

I do feel that our book/list policy can be revised. Not removed, but loosened up considerably. For book questions, this can be done by making sure that answers include a sketch of the book -- what prerequisites are assumed, the style of the book, etc.

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I'll first start out by listing the problems that can occur with such questions. If we can fix most of these, we may have a chance. Note that by "fix", I'm talking about formulating a policy that effectively mitigates these issues. I'm quite certain that SE wont implement any features specifically to

The problems

There are a couple of things that irk me about list questions in general:

• This is a Q&A site, and as such a list item is not an "answer"
• They tend to be less conceptual. One of the reasons why I like Physics.SE over Quora and PhysicsForums is that questions here are invariably about concepts.
• They may attract a lower-level crowd (like "list of Physics jokes", etc). Quora has this problem -- it's got a lot of list questions and very few high level ones.
• A single answer is almost never complete. This gets to me a lot, because it's so different in nature from other Q&As here. I can very well read the top or top 2 answers of a Q&A and learn enough. That doesn't work on list questions.
• Thy end up as a popularity contest. It's not "best answer gets voted to the top", it's "most popular answer gets voted to the top". Voting doesn't indicate the best answer, it indicates:
  • The oldest answer
  • The most popular answer

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Point #3 and partially point #4 don't really apply to book recommendations, not always.

However, book recommendation questions are unmoderatable. Unlike conceptual answers, which can be easily checked for non mainstreamness and pitching, book recommendations are hotbeds for people pitching their own publications. And also pitching irrelevant or non-mainstream books. It's not easy to moderate this, because, as moderators, we would have to read the book.

Also, note that the following problems do not occur with book recommendations on Physics (which do occur with shopping recs):

• Price issues: From what I've seen, nobody cares about price with book recommendations on Physics.
• Outdatedness: Griffiths has been used ever since Man discovered fire. Same goes for Resnick-Halliday-* and Kreyzig and the rest. While new physics books come up all the time, existing ones don't get outdated, not really. There are exceptions, though.

More about book questions, and a proposed policy to allow them

One thing that happens with book questions is that the real question being asked is "Please teach me about X". Whenever a question is narrow enough such that the topic X can be reasonably explained in a single post with links to additional reading, I feel that we should convert the post with an edit (with or without the OPs consent -- currently we have done this but only if the OP consents).

In the case of broader topics, here's what I propose:

• Only allow descriptive answers. There are lots of Physics books on a topic that can be found by an Amazon search. The question is, which one is appropriate to read? When trying to learn GTR on my own, I went ahead and borrowed Misner-Thorne-Wheeler. Big mistake. It is one of the best books in the field, but it's more of a reference -- there are better books to study from if you want to teach yourself. Thing is, you need to know what a book covers, and, more importantly, how it covers it. Does it explain tensor calculus or does it simply expect you to know it? These sorts of things are important. I've heard people talk for more than 15 minutes on the merits/demerits, style, et cetera of a physics book, so I'm sure that it's not unreasonable to ask for this. This actually makes the post really, really useful -- the reader knows his/her needs better than we do, and giving information on the style of books is a better way for the reader to determine which book to finally use. Information is always better than advice.
• The question should mention the level of understanding of the student. The topic should not be too broad, either. Also, we ought to edit in a mention of the previous point.
• We place a boilerplate banner on each question linking to a book policy and mentioning (in short) what is to be expected of answers.
• We will need the community to actively help curate book questions and enforce these policies. This is important.
• These should be made CW. Reasons? See Chris' comment
• This is an optional point: We maintain a single Community Wiki answer per question, and all other answers are incorporated and deleted as they come in.

If these policies are in place, the major problems with books questions are reduced. They're much more relevant and useful now. They also are less "all answers are equally valid"-y. They're still not conceptual, though, but this isn't so important if the answers are explanatory. I guess we could find a way to work in the non mainstream policy without forcing mods to read each book. Or just use downvotes for bad books.

List questions

I'm not really sure how to make these work. As such many of these can be improved by tweaking the language -- the language is important because changing it attracts different types of answers. A question asking for a "List of ways to measure the weight of one's head sans decapitation" will attract one-line or list-like answers with little to no explanation. When asked for a list, one's mind is focused on generating as many points as possible, without expanding on the individual points (horizontal thinking). When asked "how can I measure the weight of my head", one's mind will focus on getting a single complete solution, and post that (vertical thinking).

Some of these can't be "fixed". "List of unsolved problems in plasma Physics" -- somehow I feel that this is more suitable for a Wikipedia page. You don't learn anything from this and as such it's not conceptual.

I do see scope for improvement in the list question policy, but I'm not yet sure how to codify this. I'll mull over it and update this post when I figure something out (I'll probably have a look at past list questions etc.).

Answer 3

My take on this, and I'll expand it some more when I think about it more, is that there is a very clear good list/bad list distinction. But most of the questions people argue are good lists, I don't agree are.

Here's what makes a bad list:

1. A single answer is unlikely to be complete on its own. The question you cited that prompted this post also falls on the bad subjective side -- what one considers an "important problem" in the field may not be what others consider.
2. An answer must be continually updated. Again, the cited question falls in this category. Even if somehow we determined a complete list of "important problems," that could change tomorrow. Or next week. Or next year.

Lists of things that fall outside of those two primary issues I think would be good lists. But I'm a bit hard-pressed to come up with what those would be, and I don't recall any questions that I think would fall in that category, but that's not to say they aren't out there.

Just as we discussed with finding journals with the reference-request tag, I think questions like the one you cited are best posed in chat or on meta to indicate the tag-wiki needs to be updated to reflect the answer. For instance, the tag-wiki on plasma-physics could be updated to reflect current research areas, including key papers, journals, and reviews.

There is no need for a question/answer, that's what the tag wiki's should be used to communicate!

Answer 4

So I'm pretty late to the party and have a biased interest here, but I'll voice my opinion nonetheless.

I think sometimes lists are good. People want to organize information in a way that's easy to access and continuously update and doing it here in physics.stackexchange makes a lot of sense, because there are many high skilled people here that can contribute good value to such a list.

In my particular example, I wanted to collect a list of divergent series results that breaks the usual mold of "$1+2+3+4... -1/12$ because Casimir effect" and searching for such examples using the search feature turned up very few cases surprisingly.

I could imagine that there are other lists like this one that would be of interest to some people and so I would like to propose we allow for lists as long as they consist of a list of conceptual physics facts.

In my particular example, I am enforcing that each divergent series result comes with a reference or explanation to an actual physics result where that series came from which should be different than all the examples in the list up to that point of time.

This meta post and this actual post are the meta and actual question for the list I am trying to generate.

To back up my view further: consider this meta post. The highest rated answer starts off with a thought experiment:

"Let's suppose the purpose of Physics SE is to accumulate a database of questions/answers that are helpful to people who are trying to understand physics, and that are likely to be found by those people in a search. The keywords here are trying to understand and likely to be found."

I would argue that lots of people (especially from the math world who know about divergent series results formally, but are curious about how they manifest in physics and the other experimental sciences) would probably google for "divergent series in physics list" and ideally this post could be the first thing they run into with a long list to satiate their curiosity.

Moreover, this type of thing is very common in MathOverflow. Which is absolutely tiny compared to physics.se; see here. So I don't believe allowing lists will suddenly destroy the site, because they don't have the number of users as on Mathematics. The community should be picky about what kinds of lists they allow and don't allow, but to categorically refuse them is not a good policy, in my opinion.

Answer 5

I exactly agree with Nathaniel that good lists reasonably defined as has started doing it in this meta question should be allowed on Physics SE, as it is done on other sites in the network.

In addition to the good points already made, when considering if a list is too big or good and reasonably narrowed in scope it would be appropriate to judge things from a physics point of view too, instead of focusing on some language issues that could hint (if one wants to interpret the question like this) to a too big list. To give an example for what I mean, this question got first closed as a (big) list question because of such language issues, even though when looking at and thinking about it from a physics point of view, it is clear that there simply can not be an infinite or big number of ways the uncertainty principle can be modified in accordance with the the current experimental and theoretical physics knowledge.

In my opinion the two points brought up in tpg2114's answer constitute no obstruction to allow good list questions as defined in Nathaniel's question:

Concerning point 1, even many conceptual and technical questions can have more than one answer for good reasons, for example there exist complementary ways to look at or understand a physics issue. Looking at things from different points of view is not a bad thing in physics, on the contrary as many well known physicists agree it furthers a deeper understanding of the problem at hand and is therefore a good thing.

Concerning point 2, I think Physics SE should model itself on other sites in the network, which are targetted exclusively or inclusively at an audience of researchers. For example on Mathoverflow, CS Theory, and the former Theoretical Physics SE, questions about the current state or actual problems of a well defined enough topic or subject have always been allowed and never deemed problematic, they are even supported and appreciated by the communities of researchers there. So this second point should not constitute an obstruction to allow good list questions either.

So in summary I am all for an adjustment of the current list question policy as suggested by Nathaniel's nice post.

Answer 6

Can we please keep it to one-resource-per-answer?

Several of the answers referenced in our recent policy for resource recommendations have long answers that include multiple resources, such as this one. While this keeps things compact in a way, it makes it difficult for people to upvote specific resources. This substantially under-uses the capabilities of our platform, which is great for good answers to float up and OK ones to stay further down in the page.

So: can we make it policy that answers to resource recommendations include only one resource per answer? This involves, of course, the possibility of as many answers per user as necessary on each thread.

Two thoughts on dealing with the consequences. First, doing this opens the door to huge reputation farming. This would make a bit of an argument for making all answers community wiki - though if you come up with multiple good books and provide good reviews of them, why should you not have some rep? Secondly, it would add some initial and long-term curatorial stress in separating multi-resource answers, but I don't think this is unreasonable.