topic Re: fitting negative binomial in Proc Capability in Statistical Procedures

fitting negative binomial in Proc Capability

Al_senior — Sun, 25 Jul 2021 22:44:49 GMT

I have a dataset and I am doing exploratory analysis, I want to have a visual report showing how different distributions fit to the data. As mentioned in this SAS documentation certain distributions can easily be used in SAS.

To get what I am looking for, I am using proc capability and I pass distributions of interest in the histogram step of the following code:

ods select histogram;
proc capability data=have;
 specs usl=usl lsl=lsl;
 var result;
 histogram / normal(indices) lognormal(indices);
 by var1;
 inset mean std cv n ppk="Ppk" normal(ESTPCTgtr) lognormal(CPK) 
  normal(ksdpval) / cfill=white pos=ne;
run;

I have no issue getting the fitting line on Normal, Weibull, Lognormal, and even Beta (with some modification) on my histogram but I am unable to fit negative binomial on my data and getting the fitting line on the histogram.

Is there any way that I can do that through proc capability (so I have all fitting lines in one report and making it possible to compare visually)?

Re: fitting negative binomial in Proc Capability

SASJedi — Mon, 26 Jul 2021 16:59:09 GMT

Moved to the Statistical Procedures forum, where it should get better exposure to folks with expertise in this matter.

Re: fitting negative binomial in Proc Capability

SteveDenham — Mon, 26 Jul 2021 18:49:03 GMT

I would guess that the reason you don't get anything for the negative binomial is that the negative binomial distribution is not supported in the HISTOGRAM statement. Looking over the list of supported distributions I see that they are all continuous (no discrete distributions such as binomial, Poisson, geometric, negative binomial are listed).

SteveDenham