Pascals Triangle, Home Work and Root Cause Analysis

  • David.Poole

    SSC Guru

    Points: 75182

    Comments posted to this topic are about the item Pascals Triangle, Home Work and Root Cause Analysis

  • paul s-306273

    SSChampion

    Points: 10555

    Excellent article.

    Even better, I see you used to work in Manchester!

    Paul.

    Manchester,UK.

  • SqlOnMyMind

    SSCertifiable

    Points: 5026

    I enjoyed your article because it was relevant on multiple levels. Thank you for a well-written article!

  • eephus101

    SSC Enthusiast

    Points: 138

    Hi David,

    This is fantastic! I can find many uses for this..

    Thanks!

    John R

  • sknox

    SSChampion

    Points: 12224

    Good article.

    Of course, the point you omitted is how the actual probability of any given failure alters the calculations.

    With the lottery example, because each of the numbers is (supposedly) equally likely to be chosen, Pascal's triangle is a perfect model, and shows the true (im)probability of winning.

    With the car example, QA testing ensures that parts generally have a much higher probability of working than failing, thus although there's only one way for the whole system to work perfectly, it's more likely than the millions of ways it can fail.

  • David.Poole

    SSC Guru

    Points: 75182

    Yes, and apparently each space shuttle launch expected at least 6000 components to fail but was still designed to work.

    On my list of things not to think about is precisely how fast a piece of metal moves inside a motor-bike engine when it's between your legs:-P

  • David.Poole

    SSC Guru

    Points: 75182

    Joe, I should have remembered that. I think one of your books mentioned storing a calendar table rather than trying to workout calendar maths on the fly.

    It is so easy to forget that storing a few thousand records for utility sets costs next to nothing but delivers one hell of a lot of utility

  • richard.rabe

    SSC Enthusiast

    Points: 174

    Thanks for the great article. It reminds me of why when I used to fly airplanes my instructor kept telling me that the probability of an engine failure in a twin engine plane was twice as high as a single... of course you still had one engine running in a twin.

    do it right, or do it over and over, it's up to you

  • pmcpherson

    SSC-Addicted

    Points: 453

    Don't you also need to make sure that @n <> @r so you don't divide by 0? And @r <> 0 either.

  • pmcpherson

    SSC-Addicted

    Points: 453

    CELKO - your code does not compile. Looks like some logic is missing in the case statement.

    I don't get " SELECT fact FROM Factrorials WHERE @f = @n " I @f supposed to be a column or a variable?

    I like the idea of it and the recommendation of storing calendar data in table.

  • SQLRNNR

    SSC Guru

    Points: 281210

    Nice article.

    Jason...AKA CirqueDeSQLeil
    _______________________________________________
    I have given a name to my pain...MCM SQL Server, MVP
    SQL RNNR
    Posting Performance Based Questions - Gail Shaw[/url]
    Learn Extended Events

  • David.Poole

    SSC Guru

    Points: 75182

    As a teenager I had a job delivering potatoes to fish and chip shops across the staffordshire plains. The boss had a book called a ready-reckoner to help calculate the bills.

    I remember the books of sin/cos/tan tables, normal distribution figures etc. I also remember that they would contain small rounding errors on specific values as a means of checking whether or not a rival publisher had violated the copyright.

    My first IT job had me loading 1/4 inch tapes for backup purposes. You had to master a strange TiChi maneuver to get the ultimate efficient loading technique!

    Then there was the short straw of having to crawl through the roof space with a crimping tool to wire up a 25 pin plug to connect the mini-computer to dumb terminals. A job made harder by the fact that the boss used to bribe us with whiskey!

    Happier times, and as Phil Factor once described, a time when having an interesting personality disorder was a pre-requisite for a career in IT.

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