Correlation doesn't imply causation



  • I love this site - it keeps me at least a little bit sane. I work in 1st level support, and I suspect (or perhaps hope) that this exposes me to a much larger number of WTFs than most of you whom are lucky enough to have developer positions.

    But for my first Side Bar WTF submission I thought that I'd post a recent issue I had with my telephone line (never mind that it is a company I used to work for, posting as a customer means I won't have the same issues with anonymisation I may face with any later posts).

     

     

    Correlation doesn't imply causation

    The current XKCD** reminds us that: "Correlation doesn't imply causation, but it does waggle its eyebrows suggestively and gesture furtively while mouthing 'look over there'. "

    Correlation doesn't imply causation, but it does waggle its eyebrows suggestively and gesture furtively while mouthing 'look over there'.


    I get home one night to find my phone line completely "dead" - not dead as maybe misused to mean silent or not working, but dead as in no connection to a POTS port at the exchange, nor a connection to the DSLAM for my DSL modem. Pissed at the situation I take a stroll to see if I can suss out the issue.

    There is no obvious sign of work nor a fault anywhere along the path the line (ULL) takes to the exchange, nor at the exchange itself, but at the MDF in my building I find some clues. In addition to terminals still glistening from the fresh removal of soldered wires, and the few strands of wires which litter the floor below the box, there is a note on a card.

    The note says that a telephone technician named "Gavin" (from my phone company) came to remove a neighbour's connection from the MDF earlier that day, so that it could later be reconnected by their new "naked"-DSL provider (I think this is a WTF in itself - 2 technicians having to make 2 separate onsite visits to make a single minor change to the wiring of the twisted pair in the box).

    It is quite obvious to me at least, that despite the spaghetti cabling and the company's badly kept log book*, that they disconnected the wrong pair from inside the box.

    It takes a few calls to report the fault. The first stage in the process is denial. "There is no fault", I am told. Apparently the automated test from the exchange card says that it (the card) is functioning perfectly.

    Then there is anger. The next rep I call and speak with sees that I have already called, and decides that it is late enough that their supervisor has left and I can cop some verbal abuse - after all the automated testing has already been run and it says that I must be lying.

    Luckily, by the third rep we skip to the acceptance stage, and I get to report my fault, or at least I get to report a fault. My request to add a note to the case, "Customer requests technician check MDF" is met skepticism. I patiently explain the issue in laypersons terms (as is a big part of my job in support remember), as the rep doesn't seem to know anything other then the checklist she has been given. Somewhat surprisingly the rep is happy to be enlightened, and agrees to add my observations on the issue to the case's notes, though as she insisted on writing it based on her new found understanding of the version she wrote was likely unintelligible.

    Technicians come and they go, they check the line and the exchange and after finding no fault they suggest the fault must be inside the premises. In the visits made, none have checked the MDF. They remind me of their costs for pointing out problems in my premises or with my equipment, and insist that I stay home from work for their next visit as they will need to check the points inside my home.

    I get the necessary 1/2 day off work, and let the technician do his job. I let him rule out a basic issue within the premises and politely ask him to check that I am connected to the MDF. It doesn't take long for him to confirm that I was disconnected by his colleague and he reconnects me. He doesn't do a good job of it though and as a result my DSL has been 3/4 of the speed and my phone line static-y ever since. Yet I daren't report it, as I am sure it could all end worse (given the same bunch of line techs and reps) the next time around...



    * The log book, which has been well preserved from the 70s inside the box's door, contained no updates from the last few decades and listed a floor & premises which clearly could never have been part of the building it was apparently for.

    ** Oh, and before some of you complain about the inclusion of the XKCD comic, be nice, the comic reminded me to post this and thus I felt it warranted inclusion. I like XKCD, and if you don't then just don't read it (it's not like MFD - you don't have to read it just incase it gets better or features an Irish Girl reference)



  • You obviously knew what was going on, so why didn't you reconnect the cable yourself? Something similar happened to me once, I reconnected the cable and haven't had any problems since.

    And what does correlation or causation have to do with any of this? Sounds like an excuse just to include xkcd. Oh, and you don't have to read MFD because it might get better but because it's mandatory.



  • @SlyEcho said:

    You obviously knew what was going on, so why didn't you reconnect the cable yourself?...

    Because not being licensed, it wasn't worth the trouble. With multiple pending jobs (ie. my forementioned neighbour's reconnect and another unrelated one aswell) at the box I'd have a reasonable chance of being caught out, even if I was just fixing some of the mess.

    @SlyEcho said:

    And what does correlation or causation have to do with any of this?

    Imagine you've a program, you change some code and it stops working. I assume you'd doublecheck the code you changed before checking anywhere else. Even if your changes didn't cause the issue, in someway it seems it must relate to it.


    The phone company failed to consider a correlation between a disconnect for one tennant in a building and another complaining that their line had been disconnected that day. The phone company insisted on multiple field visits to rule out every other possible cause first. XKCD is right: "Correlation doesn't imply causation, but it does waggle its eyebrows
    suggestively and gesture furtively while mouthing 'look over there'. " That's today's lesson, and it applies to most things that you may do, not just or least coding and IT stuff. (I'm sorry, I had hoped not to rub anybody's nose in it)



  • (Interesting story,) But why is the second footnote referenced first?



  •  Ok, I've got a alternate approach. Set off a large firecracker in the MFD disconnecting the entire building and blame "those damn kids". Then sit back while your neighbours take care of the issue.



  • @DOA said:

    Set off a large firecracker in the MFD
     

    Freudian slip?



  • @Zemm said:

    @DOA said:
    Set off a large firecracker in the MFD
    Freudian slip?
    Now that you mention it that sentence works equally well with either acronym.



  • @Spectre said:

    (Interesting story,) But why is the second footnote referenced first?
     

    reverse polnic notation... ;->



  • Medical system

    I deal a lot with the medical system and I have similar complaints there.  Part of the reason that the phone company didn't correlate your effect with their cause is that six different people were responsible for different parts of the process.  The original technician made a change but he never heard about the problems it caused.  Another technician came in but he wasn't familiar with the history.  Technical support assumes that you're some know-it-all Average Joe who actually knows nothing because that's what 95% of their calls are.  Had all of your contact been with a single person, the problem would have been recognized and resolved quickly.

    The medical analogue is when you have some problem and visit a doctor.  He tells an assistant to order a test.  The assistant orders it, but the details of the order are not quite right because she doesn't know why it was ordered.  The details make the test cost $500 more than necessary, but of course the assistant has no idea about the costs of such things.  When you get to the radiologist for the test it is performed by a technician who has never seen you before.  Your appearance or comments might provide clues to the diagnosis, but it doesn't matter since the person reading the films is in another building.  He also doesn't have any of your previous medical records for background.  He writes a report and has it faxed to your doctor.  Your doctor gets the written report -- he has some questions about it but can't reach the radiologist (through three more layers of bureaucracy) during your office visit, so you get sent for another round of tests rather than having your problem solved by someone who can see the whole picture.



  • @DOA said:

    @Zemm said:

    @DOA said:
    Set off a large firecracker in the MFD
    Freudian slip?
    Now that you mention it that sentence works equally well with either acronym.

     

    My ISP is TPG which is close to another Internet TLA... ;-)


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