PARAMETERS Statement

The NLIN Procedure

PARAMETERS Statement

PARAMETERS parameter=values ... ;

PARMS parameter=values ... ;

A PARAMETERS (or PARMS) statement must come before the RUN statement. Several parameter names and values can appear. The parameter names must all be valid SAS names and must not duplicate the names of any variables in the data set to which the NLIN procedure is applied. Any parameters specified but not used in the MODEL statement are dropped from the estimation.

In each parameter=values specification, the parameter name identifies a parameter to be estimated, both in subsequent procedure statements and in the output. Values specify the possible starting values of the parameter. Usually, only one value is specified for each parameter. If you specify several values for each parameter, PROC NLIN evaluates the model at each point on the grid. The value specifications can take any of several forms:

m: a single value
m1, m2, ... , mn: several values
m TO n: a sequence where m equals the starting value, n equals the ending value, and the increment equals 1
m TO n BY i: a sequence where m equals the starting value, n equals the ending value, and the increment is i
m1, m2 TO m3: mixed values and sequences

This PARMS statement specifies five parameters and sets their possible starting values as shown:

   parms  b0=0
          b1=4 to 8
          b2=0 to .6 by .2
          b3=1, 10, 100
          b4=0, .5, 1 to 4;

Possible starting values

B0 B1 B2 B3 B4

0 4 0.0 1 0.0

5 0.2 10 0.5

6 0.4 100 1.0

7 0.6 2.0

8 3.0

4.0

Residual sums of squares are calculated for each of the 1 ×5 ×4 ×3 ×6 = 360 combinations of possible starting values. (This can take a long time.) See the "Special Variables" section for information on programming parameter starting values.

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Possible starting values
B0	B1	B2	B3	B4
0	4	0.0	1	0.0
	5	0.2	10	0.5
	6	0.4	100	1.0
	7	0.6		2.0
	8			3.0
				4.0