topic Re: Proc NLIN : parameter array confusion when initial values are given in dataset in Statistical Procedures

Proc NLIN : parameter array confusion when initial values are given in dataset

PGStats — Tue, 08 Sep 2015 16:55:57 GMT

In the simplified NLIN example below, giving initial values to model parameters in the PARAMETER statement is NOT equivalent to specifying them in a dataset. It looks like parameter names are not known at the time of array definitions when the parameters are given in a dataset. Is this an undocumented "feature"?

/* Parameter array given initial values in PARAMETER statement. Works fine. */
proc nlin data=sashelp.class;
parameters w=1 h=1;
bounds w h >= 0;
array x{*} weight height;
array y{*} w h;
s = 0;
do i = 1 to dim(x);
s = s + x{i}*y{i};
end;
model age = s;
run;

/* Same problem. Parameter array given initial values in PDATA dataset. Doesn't work. */
data pd;
Parameter="w"; Estimate=1; output;
Parameter="h"; Estimate=1; output;
run;

proc nlin data=sashelp.class;
parameters / pdata=pd;
bounds w h >= 0;
array x{*} weight height;
array y{*} w h;
s = 0;
do i = 1 to dim(x);
s = s + x{i}*y{i};
end;
model age = s;
run;

ERROR: The variable y was referenced but not given a value.

Re: Proc NLIN : parameter array confusion when initial values are given in dataset

Rick_SAS — Tue, 08 Sep 2015 17:13:59 GMT

I am pleased to report that your code runs without error in SAS/STAT 14.1 (released in July 2015 with SAS 9.4m3). Consequently, it looks like someone agreed with you that this "feature" was not ideal.

By the way, try the new SAS color-coded editor in the new COmmunity. Click the "running man" icon when you paste in the code. It will appear color coded.

Re: Proc NLIN : parameter array confusion when initial values are given in dataset

PGStats — Tue, 08 Sep 2015 17:44:54 GMT

Thank you Rick!