+ Reply to Thread
Results 1 to 4 of 4

Thread: Need help with probability question

  1. #1
    Points: 4, Level: 1
    Level completed: 7%, Points required for next Level: 46

    Thanked 0 Times in 0 Posts

    Need help with probability question

    So here's my problem:

    a typical physician performs 4,000 procedures/services per year. These are made up of 75 unique procedures/services. If I were to select 30 line items (each being a reported service or procedure), what is the probability that each of the 30 in the sample would represent one of those 75 unique services or procedures such that each of the 30 were a unique service/procedure? Thank you for your help and feel free to respond to me directly at fcohen7777@gmail.com
    Last edited by Slade Steele; 10-12-2015 at 06:11 PM. Reason: Clarify the question

  2. #2
    Omega Contributor
    Points: 38,392, Level: 100
    Level completed: 0%, Points required for next Level: 0
    hlsmith's Avatar
    Not Ames, IA
    Thanked 1,186 Times in 1,147 Posts

    Re: Need help with probability question

    Not totally following your question. The probability of selecting procedure would be the number of those procedures over the total number of procedures.

    Once you select one then you just adjust your numbers. Please provide a little more clarity. Thanks.

  3. #3
    TS Contributor
    Points: 12,227, Level: 72
    Level completed: 45%, Points required for next Level: 223
    rogojel's Avatar
    I work in Europe, live in Hungary
    Thanked 332 Times in 312 Posts

    Re: Need help with probability question

    pick a procedure. If the procedure was performed n times the probability of getting a sample of 30 consisting of only that one will be

    Prob =( n*(n-1)*......*(n-29))/(4000*3999*.....*3971)

    using the hypergeometric distribution.


  4. #4
    TS Contributor
    Points: 22,410, Level: 93
    Level completed: 6%, Points required for next Level: 940

    Thanked 565 Times in 537 Posts

    Re: Need help with probability question

    For the problem itself, if a certain procedure/services is allowed to be not performed in a year, then the number 4000 is redundant and you just need to model by a multinomial distribution.

    In such case the probability of having a specific 30 procedure to appear exactly once each will be

    \frac {30!} {1!^{30}} \left(\frac {1} {75}\right)^{30}

    For the generic case, you multiply the above probability by

    \binom {75} {30}

    However, things become more complicated if you are given that they must happen once each in the 4000 procedures. You are now facing truncated version of multinomial distribution. Let see the above fits your model or not first.

+ Reply to Thread


Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts

Advertise on Talk Stats