topic Re: Get goodness of fit tests for weibull distribution in Statistical Procedures

Get goodness of fit tests for weibull distribution

SB2017 — Tue, 28 Mar 2017 13:56:29 GMT

Hello,

I am trying to fi a weibull distribution to a list of frequency data, and I am using the following code in SAS 9.4

proc univariate data=data1;

var group;

freq count;

histogram / weibull (Theta=est) midpoints=1 to 28 by 1;

run;

I got my parameter estimates however SAS did not give me any Goodness of fit statistics. Is there a specific coding that allows me to get one?

Thank you

Re: Get goodness of fit tests for weibull distribution

Rick_SAS — Tue, 28 Mar 2017 14:03:04 GMT

You code looks correct and should give GOF tables. Run the following and see if you see the "Goodness-of-Fit Tests for Weibull Distribution" table

ods trace on;
proc univariate data=sashelp.cars;
   var mpg_city;
   freq cylinders;
   histogram mpg_city / weibull (Theta=est) midpoints=10 to 60 by 2.5;
run;
ods trace off;

Re: Get goodness of fit tests for weibull distribution

SB2017 — Mon, 19 Jun 2017 20:41:12 GMT

The proposed code did not gice GOF tables unless c>2. I had to put in a value of theta to getW-sq and A-sq GOF statistics.

Is there another procedure available to fit a weibull distribution using point frequency data?

Thank you

Re: Get goodness of fit tests for weibull distribution

Rick_SAS — Mon, 19 Jun 2017 23:53:57 GMT

Yes, the documentation for the GOF tests in PROC UNIVARIATE mentions that the ECDF tests for GOF are only available when c > 2.

I'm not near a copy of Stephens and D'Agostino right now, so I can't look up why that constraint is required.