Skip to content

Non standard Beta Distribution

5 messages · Collins Ochieng Onyanga, David Winsemius

Original
Collins Ochieng Onyanga
# 
Hello everyone,

I am trying to fit fit a non standard Beta distribution to a data set  but
so far I have not succeeded. Can anyone help me with a code in R that can
do this.

Thanks.

-- 

Collins Ochieng onyaga
AIMS Tanzania student 2016/2017
Skype: collins7952
Collins Ochieng Onyanga
#
On 4 May 2017 at 01:00, Collins Ochieng Onyanga <collins at aims.ac.tz> wrote:

            

      
      
      
    

        
-- 

Collins Ochieng onyaga
AIMS Tanzania student 2016/2017
Skype: collins7952

  
    

      
      
    

  


  


      

    

    

      
      

        


  

        

      David Winsemius
    

    

      
      #
    

  


  

          

      
      
      
    

        
To Collins Ochieng Onyanga; 

This is the third identical message to rhelp in the span of 2 hours. Please increase the interval over which you remain patiently waiting for a reply.

You are application for subscription to the list has been processed. You were advised in the information page that processing a first posting might take a full day. 

(To the other list member's, I apologize. I can see no method of accepting a subscription requestg while at the same time rejecting or discarding a duplicate (or triplicate) posting while using the Mailman management interface.)

David Winsemius

            

      
      
      
    

        

      
      
    

        
David Winsemius
Alameda, CA, USA

  
  


  


      

    

    

      
      

        


  

        

      Collins Ochieng Onyanga
    

    

      
      #
    

  


  

      
Hi,

I would like to fit a non standard beta distribution with the two scale
parameters and lower and upper boundaries to data like  the one shown
without normalizing it.

[1] 37.50 46.79 48.30 46.04 43.40 39.25 38.49 49.51 40.38 36.98
40.00[12] 38.49 37.74 47.92 44.53 44.91 44.91 40.00 41.51 47.92 36.98
43.40[23] 42.26 41.89 38.87 43.02 39.25 40.38 42.64 36.98 44.15 44.91
43.40[34] 49.81 38.87 40.00 52.45 53.13 47.92 52.45 44.91 29.54 27.13
35.60


I have tried using the following code;

fitdist((Z1-r)/(t-r) , "beta", method = "mme",lower=c(0,0))

but with this I am normalizing the data to be in the interval (0,1) .


Thanks.

        
On 4 May 2017 at 03:27, David Winsemius <dwinsemius at comcast.net> wrote:

        

            

      
      
      
    

        

      
      
    

            

      
      
      
    

        

      
      
    

            

      
      
      
    

        
-- 

Collins Ochieng onyaga
AIMS Tanzania student 2016/2017
Skype: collins7952

  
    

      
      
    

  


  


      

    

    

      
      

        


  

        

      David Winsemius
    

    

      
      #
    

  


  

          

      
      
      
    

        
So what's wrong with using that approach? If you try to re-invent the wheel, you will lose efficiency since dbata, qbeta and pbeta are all coded in C. Is the back-transformation difficult? 

The help page for fitdistrplus::fitdist has a worked example of defining a three-member dpq-distribution family. Admittedly the mathematical expression for the more general presented at the NIST document is mildly complex, but this now appears to be a request to satisfy a homework assignment. I never took a math-stats course, but this task doesn't appear particularly difficult, only tedious. And the Posting Guide says rhelp is not for homework. That rule would probably be relaxed if you showed greater effort at creating a 3 member set of gbeta distribution function, but I haven't seen that level of effort yet.