<p>The answer by <a href="https://stats.meta.stackexchange.com/users/805/glen-b">Glen_B</a> regarding the optimal use of the <code>self-study</code> tag is helpful to me, but I would like to offer another perspective involving some practical difficulties I have encountered when approaching these types of questions.  (I am not a very experienced user compared to some others, so maybe I am still finding my footing with these questions.)  Certain questions are easily identified as textbook questions, but sometimes it is hard to gauge how "routine" a question actually is.  There are also some other practical problems I encounter when I approach these questions:</p>

<ul>
<li><p><strong>Practical Problem 1:</strong> The goal of the site is to give answers that are elucidating to a broad readership, and not just the specific questioner.  However, in the <code>self-study</code> questions the analysis of the question is limited by asking the OP where he/she got stuck, and addressing a hint to assist progress with this part of the solution.  You could have different questioners all asking the same statistical question, but they are getting stuck on different parts.  This makes the answers very specific to the OP and not necessarily very useful for other readers who are also interested in how to solve that type of question.  Thus, there is a tension between giving an answer of broad interest to readers, versus giving a hint to a specific OP that is stuck on one specific part of a question.  </p></li>
<li><p><strong>Practical Problem 2:</strong> Often the best kind of "hint" for a problem is to show how one or two missing mathematical steps can be done to get further in the problem.  Sometimes this can be alluded to by telling the OP to apply "so-and-sos Law", but sometimes this is insufficient and you need to show how it is applied in context, which means you are actually doing one or two mathematical steps for them.  However, writing out mathematical steps properly requires preliminary context and definitions, which means you may have to write out all preliminary definitions and steps up to that point to make sense.  If the "road-block" in the question comes near this end, this is pretty close to giving a full answer already.  So in these cases you are trying to figure out how to show some steps (e.g., applying some law) without giving something that is pretty close to a full solution.</p></li>
<li><p><strong>Practical Problem 3:</strong> Questions with the <code>self-study</code> tag vary enormously in their level of difficulty.  Some are routine undergraduate textbook questions and some are difficult theory questions.  One <a href="https://stats.stackexchange.com/questions/355978/finding-a-function-minimizing-the-expected-value/358488#358488">recent <code>self-study</code> question</a> was a functional optimisation problem that is at least at graduate level, and is even a whole new area of study for most graduate students.  (Arguably this was mistagged, since the problem is hardly routine.)  Such readers mostly have not seen functional optimisation <em>at all</em>, and the only way they will understand it is if you step them through the whole process.  It is useless to give a "hint" in this case, because the problem is at a high level and the OP does not know how to start, or how to do any of the later steps.  They don't even know how to <em>frame the question</em> accurately.</p></li>
<li><p><strong>Practical Problem 4:</strong> Many questions with the <code>self-study</code> tag are old enough that the OP has finished whatever course raised the question.  (Some are five years old; the OP has probably graduated and entered the workforce!)  There is a hint given, but the OP does not come back and show the solution obtained with the hint.  In this case a full answer does not advantage the OP, but it remains in the repository of answers that other students can look up.  As noted above, for the broader readership, they are interested in the overall question and its solution, and not necessarily the exact hint relevant to that OP.  So in this case there is no advantage to the OP in giving a full solution, which militates further in favour of an answer that is useful to a broad readership.  In this case, what is a reasonable "hint" for an OP who asked a question five years ago?</p></li>
<li><p><strong>Practical Problem 5:</strong> The OP is allowed to bypass the restriction on giving a full answer, but other users are not.  This seems quite arbitrary.  If full answers are a problem then they are a problem; why would they not be a problem if they come from the same user that posts the question?  (To my mind, this illustrates that the purpose of this tag is horribly confusing.)</p></li>
</ul>

<p>I am still fairly new to answering these questions.  As with <a href="https://stats.meta.stackexchange.com/users/805/glen-b">Glen_b</a>, it is possible I will come to understand them better with experience, so I apologise in advance if any of what I am saying is silly.  Still, I find it a bit confusing deciding how to approach some of these questions.</p>

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<p><strong>An aside:</strong> In regard to these questions, I also tend to agree with <a href="https://stats.meta.stackexchange.com/users/39630/carlos-cinelli">Carlos</a> that a repository like this would actually be really great, and it should not be the responsibility of CV users to enforce self-control on students.  I realise this issue has been discussed, so I will just leave this remark here as dissent from the majority view.  The practical difficulties above emerge regardless, but I don't actually agree that it is a problem if CV has a repository of solved textbook questions.</p>

<p>It is certainly true that students can skip-out on learning problems by looking up answers on CV.SE, but universities have methods for testing student knowledge independently of this; if a student gets their answers from CV and does not learn the material then he/she will not be able to pass an exam.  Is it really up to us to enforce a barrier to knowledge to deal with a student who tries to avoid learning - <em>a fortiori</em> when the student still needs to be able to pass examinations without access to CV experts?</p>
