The Engineering.SE policy on check-my-work questions

Question

We have recently received a few check-my-work questions:

• Heat Loss per Linear Ft

• Problem with Energy Transfer Rate Conversion

• https://engineering.stackexchange.com/questions/3687/standard-thickness-of-a-steel-air-receiver

• Band Brake placed Perpendicular to the Diameter bisecting the Angle of Contact

These questions begin with a homework-like question, show some work, and end with phrases like 'Am I missing anything?' or 'What am I doing wrong?'.

Should questions such as these be on-topic here? If we want to allow some of these questions, how do we distinguish the on-topic ones from the off-topic ones?

Answer 1

Part of me wants to help solve problems, and part of me wants to to keep the site focused on useful questions and answers.

Background

My day job is an Engineer (in the strict sense of the term). I went to school and had a lot of engineering courses. I have notes from those classes. Whenever I have had "real engineering problems", my notes are practically useless. This quickly showed me that the most useful part of class was getting the ideas right and less getting the math right.

Check My Work

The types of questions that we are discussing are mostly useless to anyone other than the asker. These are also the types of questions that are best answered by TAs or during office hours.

I would like to take the middle ground (similar to Air's answer) and say, "Answer the question, then later close it since it is no longer useful." The problem is that to take that logic to the end result, you then have to ask yourself why would you spend time on something that is later going to be closed/removed.

Lasting Value

As long as a question has lasting value, it should stay. To define this term, it has to be more about theory or practice and less about math.

Not understanding something is OK. Not doing the math correctly is not OK.

Questions about understanding why the math is not OK is probably OK.

Answer 2

First, an observation that homework questions are currently on-topic in so far as they present clearly-defined engineering problems and we previously decided against declaring them off-topic. We could revisit that discussion—especially considering that the runner-up answer links to a policy on Physics SE that seems to address this exact issue—but phrases like you describe can often be edited out and are less defining characteristics than warning flags.

Here is where I'll start to disagree with Glen's answer.

I think it's significant that both the linked problems are ultimately caused by an error of process rather than of approach. The first probably would have been avoided by sketching out the geometry of the problem; or at least if the problem was actually one of misunderstanding what "one inch of pipe insulation" means, a sketch would have made that clear. The second is either a brain fart or a really basic conceptual deficit. As the summary of the Physics policy suggests, it's better for all parties if these problems are solved individually, whether that means in a face-to-face with an instructor or TA, over email with a friend, over coffee with a colleague or even in our chat room.

There's nothing wrong with pointing out to the OP what they did wrong—I would do it in a comment rather than an answer—but any question that turns out to be nothing more than a game of "spot the miscalculation" has no lasting value for the site and should be removed (in due time).

I propose that we handle these by taking a cue from Stack Overflow's custom close reasons:

This question was caused by a problem that can no longer be reproduced or a simple typographical error. While similar questions may be on-topic here, this one was resolved in a manner unlikely to help future readers. This can often be avoided by identifying and closely inspecting the shortest program necessary to reproduce the problem before posting.

We would probably drop "could not be reproduced" and change "typographical error" to something along the lines of "arithmetic error." I'm not proposing a specific wording in this answer because it's not clear that a custom close reason will be necessary yet.

Answer 3

I think those sorts of questions are okay with some minor editing.

My personal preference is to see the assignment clearly called out and then the correct answer noted. I think it's courteous to the community to indicate that it's homework so that the scope of the question is a bit better defined. That allows the community to switch into a "theoretical only" type mode and remove considerations that might be applied in a real world scenario.

Those two questions meet our guidelines regarding homework problems in that they show the related equations and the OP has attempted to solve the problem.

I didn't close this question as a duplicate of the earlier homework question because I think you're asking about a nuance that hasn't been addressed yet.

These questions begin with a homework-like question, show some work, and end with phrases like 'Am I missing anything?' or 'What am I doing wrong?'.

_{emphasis added}

I didn't particularly like the end phrasing on those questions as there's an obvious answer of "Yes, you're missing something because you didn't get the right answer." And as much as I find pedantry amusing, I think the community can be more constructive than that.

I think that the right approach is to edit that portion of the question and help focus things on what the actual problem appears to be.

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Taking a broader perspective, it's fair to think about what percentage of the site we want homework questions to represent.

I'll admit my bias towards conceptual problems appearing to be more interesting. And my own preference would be to have homework questions be in the minority. My Programmers and StackOverflow profiles reinforce that bias.

But I would be foolish to not acknowledge the successes that StackOverflow has had. And that success is due in part to handling very focused homework questions like the ones we're currently allowing.

So while I may not want homework questions to represent the majority of the site, they certainly don't hurt at lower volumes and I think we're still on the right side of that balancing point.

Answer 4

I'd actually like to see another SE site created that is specifically for checking of work. This would be similar to the way the programming/software engineering discipline is broken into a subset of sites.

Since the sites related to this discipline are arguably the most mature and most developed area within the SE universe, I think we can look at their model as emulable for other disciplines.

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As it relates to "check my work" questions, the programming sphere of SE has this handled pretty well I think - we can look at emulating the division between StackOverflow and CodeReview, and could create our own sub-divisions by having EngineeringOverflow and EngineeringReview sites. If we follow this model a step further we could create a third site Engineers as the parallel to the Programmers site.

I see this multi-site subset of Engineering comprised as:

• EngineeringOverflow : for specific questions regarding engineering challenges you are trying to overcome.

• EngineeringReview : where you can post up working solutions for peer review and get suggestions for improvements (check my work questions, continuous improvement questions, etc. would go here)

• Engineers : for discussing general Engineering concepts, theories, and practices.

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Examples:

• Question: I'm putting together a test plan, and struggling with determining the number of samples needed. I want to ask a question on how to determine the number of test samples needed to reach a 95% confidence level on mean time between failures (MTBF) for an unknown (infinite) population size.

  On-Topic for: EngineeringOverflow. This is a specific question regarding calculations related to reliability engineering and construction of test plans.

• Question: I'm a design engineer at a small company. One of the design requirements is that the product must achieve a specific minimum mean time between failures in the field. As a small company, we don't have a reliability engineer in house and I've been asked to design this test plan since I'm the cognizant engineering on the project. I've created a test plan, but since this is a little outside my normal scope of work, and this is a high visibility project, I'd like to get some peer review on my approach before presenting my plan to the man in charge.

  On-Topic for: EngineeringReview. I have a solution and would like to have it peer reviewed.

• Question: Same scenario as above, but before creating my plan I'd like to get some general advice on distinguishing between mean time between failures (MTBF) and mean time to failure (MTTF), and where to draw the line on "repairable" vs "non-repairable" failure modes. This will help me decide whether or not MTBF is the appropriate metric to focus on, or if MTTF is what we really need (as I suspect it is).

  On-Topic for: Engineers. Looking for advice on the general topics of test plan scope and data categorization, as well as defining industry terminology.

Answer 5

There needs to be a balance between doing a student's homework for them and helping them understand the basic engineering principles behind the problem such that they can do it on their own.