+ Reply to Thread
Results 1 to 3 of 3

Thread: Distribution of p-values

  1. #1
    Points: 8,411, Level: 61
    Level completed: 87%, Points required for next Level: 39

    Posts
    20
    Thanks
    0
    Thanked 0 Times in 0 Posts

    Distribution of p-values




    Hello

    By way of some background, I have a data set with 160 observations. Each observation is a patient and the variable of interest is the number of appointments each had over a 5 month period. The question is whether there has been a decrease in patient appointments given what we could expect from their previous history. I'm comparing the number of appointments to the outcome of a model that predicts, based on each patients previous history, how many appointments we can expect in five months.

    As the expected numbers are the output of a random model I ran the analysis 10,000 times and with each iteration I carry out a wilcoxon test in R with an alpha = 0.1, the alternative being less than the expected and I note the p value.

    I now have 10,000 p values and find that 6790 are below alpha (0.1). Is it a simple case of running a binomial test (x= 6790, n = 10000, prob of success each trail = 0.1) to determine if these results are themselves significant and conclude that it would be unlikely to have so many significant results if there was no difference?

    Andrew

  2. #2
    TS Contributor
    Points: 6,786, Level: 54
    Level completed: 18%, Points required for next Level: 164

    Location
    Sweden
    Posts
    524
    Thanks
    44
    Thanked 112 Times in 100 Posts

    Re: Distribution of p-values

    I think so, yes. The P-values are uniformly distributed under the null.

  3. #3
    Points: 8,411, Level: 61
    Level completed: 87%, Points required for next Level: 39

    Posts
    20
    Thanks
    0
    Thanked 0 Times in 0 Posts

    Re: Distribution of p-values


    Thanks Englund.

    If the p values are uniformly distributed under the null, should the probability of success in the binomial test be 0.5 rather than the alpha used (0.1)?

    Thanks again for the help.

+ Reply to 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