R^2 is unfortunately not a part of the output from the nonlinear regression (e.g. below) in the newer versions of SAS. But I need the adjusted r2 value or simple r2 (coefficient of determination) for my research manuscript. Please kindly modify my below proc programming that could also estimate the R2. Many thanks
Here is the complete data, please use it if you want
data large;
input sow stw time;
datalines;
4 3.366 3
4 3.052 6
4 2.666 9
4 2.755 12
4 2.203 15
4 1.886 18
3.982 1.525 21
3.882 1.547 24
3.393 0.81 27
3.586 0.76 30
2.295 0.27 33
3.475 0.67 36
;
proc nlin data=large method=marquardt;
parms B=0.5 R=0.1;
delta=0.000001;
s=sow**(1-B)-R*(1-B)*time;
if s>0 then stx=s**(1/(1-B));
else stx=0;
model stw=stx;
sb=(sow**(1-B+delta)-R*(1-B+delta)*time);
if sb>0 then sdb=(stx-sb**(1/(1-B+delta)))/delta;
else sdb=0;
der.B=sdb;
sr=(sow**(1-B)-(R-delta)*(1-B)*time);
if sr>0 then sdr=(stx-sr**(1/(1-B)))/delta;
else sdr=0;
der.R=sdr;
output out=largep p=pstw;
run;
