/*****************************************************************************************************************

SAS file name: Neg_Binomial_Curves.sas
File location: 
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Purpose: To draw densities for three different negative binomial distributions
Author: Peter Clemmensen
Creation Date: 12/06/2017

This Program supports the Example page "Negative Binomial Distribution" on SASnrd.com

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/* Negative Binomial Probability Mass Function Data, holding p fixed */
data negbin_PMF_n;
   do n=0, 2, 5;
      do k=0 to 10;
         pmf=pdf('negbinomial', n, 0.5, k);
         output;
      end;
   end;
run;

/* Draw PMF Curves */
title "Negative Binomial Probability Mass Function";
title2 "For Different Values of n, fixing p=0.5";
proc sgplot data=negbin_PMF_n noautolegend;
   series x=k y=pmf / markers group=n lineattrs=(thickness=2) markerattrs=(size=10 symbol=circlefilled);
   xaxis values=(1 to 10) label='k' labelattrs=(size=12 weight=Bold);
   yaxis display=(nolabel);
   keylegend / title="n =" titleattrs=(Size=12 Weight=Bold) 
               position=NE location=inside across=1 noborder valueattrs=(Size=12 Weight=Bold);
run;
title;

/* Negative Binomial Probability Mass Function Data, holding n fixed */
data negbin_PMF_p;
   do p=0.25, 0.5, 0.75;
      do k=1 to 10;
         pmf=pdf('negbinomial', 5 , p, k);
         output;
      end;
   end;
run;

/* Draw PMF Curves */
title "Negative Binomial Probability Mass Function";
title2 "For Different Values of p, fixing n=10";
proc sgplot data=negbin_PMF_p noautolegend;
   series x=k y=pmf / markers group=p lineattrs=(thickness=2) markerattrs=(size=10 symbol=circlefilled);
   xaxis values=(1 to 10) label='k' labelattrs=(size=12 weight=Bold);
   yaxis display=(nolabel) values=(0 to 0.15 by 0.05);
   keylegend / title="p =" titleattrs=(Size=12 Weight=Bold) 
               position=NW location=inside across=1 noborder valueattrs=(Size=12 Weight=Bold);
run;
title;