All entries for Thursday 05 December 2019

December 05, 2019

The "XY Problem" or how to ask so somebody can answer

There's a lot of things that I feel ought to have pithy names or words, and this is one of them. The classic "XY problem" goes: Person wants to solve problem X. They don't know how. They think about it, and conclude that they will need to do "Y" as part of the solution. They don't know how to do this either. So they ask for help, but omit, or forget, to mention the larger problem. This can lead to bad or not-applicable answers, and an inability of the (presumably) skilled responders to explain how to do X. Since the original asker doesn't know how to do X, there's a good chance "Y" was a poor approach, or irrelevant, or harder than it needs to be etc.

I managed to commit a classic XY swap today while knocking up a very simple bash script. I wanted to take a filename, and strip its extension off. I knew this was going to be ".f90" in context, so I searched for how to strip the last 4 characters of a string in bash. I found this questionand used the substring solution given, before reading a bit more of the page and realising that I (and the original asker) were asking the wrong question. We both actually wanted this solutionto remove the dot and the extension. Funnily enough, this is also the archetype XY problem, as described at e.g. hereor here.

In this case, it isn't a big problem. Both solutions work, and for my actual use I don't need to gracefully handle a string without the ".f90" extension at all. But in more "interesting" (i.e potentially serious and causing of harm) cases on some of the forums I read (e.g. DIY, powerlifting, cybersecurity) the asked question hides a serious misunderstanding and goes off down an unhelpful path. For example, thankfully this guyasked his question openly (why are is breakers tripping after he removed a cooker fan and tied the live to the neutral wire) even if it was rather too late! Somewhere in the hundreds of questions about tripping breakers on that forum, there is probably somebody who's done something just as bad, but hidden it.

Another amusing type is the one where the question as asked can be answered effectively, but the asker would be surprised by the extra information. For instance (summarised from a real exchange):

A: I need a workout program that takes 3 hours every day!
B: Here are some! They're awesome!
C: Hold on, why do you want this?
A: Because I'm bored and I need to occupy 3 hours.
C: Jeepers! Find a hobby buddy! Forcibly spending a fixed amount of time is not going to lead to productive training...

But it Works, Doesn't it?

Even when the question isn't the right one, it is possible to get a solution which "works". But assuming you're trying to improve your programming skills, there's a lot wrong with "good enough" and the "wrong" solutions often have a whole host of problems:

They're too specific. For example, the substring solution for my file-extension problem works, but it's less general than it should be. It only works for 3 character extensions (plus one for the '.') and gets the wrong answer if there is no extension, wheras the actual solution works in both of those cases.
They're misleading when read back. Again, with the file-extension problem it's not clear what I'm doing by taking 4 characters off - the purpose is much clearer if I split on the dot.
They're not actually any quicker/simpler than the "proper" solution. The file-extension thing is a good illustration again - bash substrings are kinda inelegant, while pattern substitutions aren't. The "proper" solution is shorter and much clearer in general.
You still don't know how to solve the "actual problem" where you could have learned a much broader-applicable thing and improved your problem solving ability. In a lot of cases, you end up writing "Fortran in every language" rather than actually learning the approch of the one you're in. Again, the file-extension example is a good one. Doing it with a string slice is something familiar to me from other languages, but not a good move in bash, and it makes the problem more fiddly (I need to find the string length because of how substringing works).
Last and perhaps most egregiously, it hides from YOU how well you understand what you're doing, and how hard it actually is. My hacky solutions can end up being far more complex than they need to be, or they can end up making a genuinely hard problem look simple, because they don't actually solve it. See, for example, the difference between a genuine AI chatbot and the ELIZA model.

So what's the solution?

Mostly, when asking a question, try to ask the actual real one. This is easy when asking a question (in person or in text), but gets a bit tricky when using a search engine, since you're having to break things down into just a few key words. But the general idea is to look for the overall problem, as well as the partial solution you've thought up, to think very hard about what that actual problem is, taking a step back if required, and to not get too attached to your approach.

Always bear in mind that a complete change of tactic might be required to actually achieve your goal, and that you might not have quite nailed down what that goal is yet. And keep in mind the quote from Henry Ford: