*/BIOMASS YIELD AND QUALITY FOR EFAW Linear plateau model;
dm'log; clear; output; clear';
 
DATA one;
input x y;
cards;
225	12847
30	14636
0	17238
150	15449
75	18051
150	17726
30	19678
75	18539
225	15775
0	18702
0	18490
150	27906
75	24572
225	26670
30	25760
150	22149
225	25158
0	29728
75	32574
30	20588
30	20653
75	21304
150	19678
225	19352
0	18377
150	17889
75	14961
0	11872
30	10245
225	11384
75	16262
30	17726
150	15287
0	18377
225	16750
0	17157
150	25776
225	27223
30	19612
75	24036
150	8456
75	10408
225	12522
0	13335
30	10571

;

proc nlin data = one best = 3;
  parms b0=1000 to 15000 by 500 b1=10 to 100 by 10 njoint=50 to 80 by 5;
  if x<njoint then do;
  model y = b0 + b1*x;
der.b0=1;
der.b1=x;
der.njoint=0;
end;
else do;
model y=b0+b1*njoint;
der.b0=1;
der.b1=njoint;
der.njoint=b1;
end;
file print;
if _obs_ =1 and _model_ =0 then do;
  plateau = b0 + b1*njoint;
  put plateau=;
end;
  plateau=b0+b1*njoint;
id plateau;
  output out = new p = pry parms=b0 b1 njoint sse=sse;
run;
proc plot;
plot y*x='+' pry*x='*'/overlay;
run;
proc means noprint;
var y sse b0 b1 njoint plateau;
output out = new2 n = tdf
mean = y sse b0 b1 njoint plateau
css=csst;
data new3; set new2;
intercpt=b0; slope=b1; joint=njoint;
rsq=(csst-sse)/csst;
edf=tdf-3;
ssr=csst-sse;
msr=ssr/2;
mse=sse/edf;
f=msr/mse;
probf=1-(probf(f,2,edf));
keep intercpt slope joint plateau rsq f probf;
proc print;
run;