Percentile calculation

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nadia aziz
2009-11-18
2013-04-29
  • nadia aziz

    nadia aziz - 2009-11-18

    Hi,

    Is there a way to calculate percentile of a set accurately? I made use of the percentile function as on the mondrian.pentaho.org site,but the results are not as per expected. What is the best way to calculate a 95 percentile of a set?

    Thanks
    naaziz

     
  • Julian Hyde

    Julian Hyde - 2009-11-20

    What answer were you hoping to get? Given the set {10, 20, 30, 40, 50}, what is the 95th percentile?

     
  • nadia aziz

    nadia aziz - 2009-11-20

    Hi,
    I expect to get 50,(rounded up). In my case I have the following: Number of tickets that must be arranged according to the resolution time taken to solve them, and i must have the 95th percentile of this list. I must have an answer of the reoslution time at the 95th percentile position, and the ticket reference at this position.
    At the moment I used Percentile function and put in calculatedMember, formula="Percentile(..Children, ,95)"
    But with this approach I havent got the correct answer.

    Thanks,
    Nadia

     
  • Julian Hyde

    Julian Hyde - 2009-11-23

    You should get something interpolated between 40 and 50. Specifically, 47.5, because 40 represents 80% and 50 represents 100%, and 95% is 3/4 of the way from 80% to 100%, and 47.5 is 3/4 of the way from 40 to 50.

     
  • nadia aziz

    nadia aziz - 2009-11-23

    hmm,, What I expect is as follows: Imagine I have a set of tickets against the amount of time taken to resolve them,
    so as follows

    {T9 90]

    then I should get amount of time taken was 90seconds. I dont know if i was able to explain this to you well enough. I do not wish to get interpolated numbers, infact I need to have numbers that in the dbase,

    thanks
    naaziz

     
  • Julian Hyde

    Julian Hyde - 2009-11-28

    Mondrian's Percentile function is consistent with standard MDX behavior.

    If you don't want interpolation, use Percentile to find the interpolated value (e.g. 95) then use Filter and Tail to find the last value that is less than or equal to that interpolated value (90). You might find the Rank function useful also.

    Julian

     
  • nadia aziz

    nadia aziz - 2009-12-03

    Thankyou,

    I tried it in one more way, may be very poor. I did a sort, and then a topcount . I get the answer more suitable to what i wanted.

    naaziz

     

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