MODEL PROGRAM Command (NLR command)
The MODEL PROGRAM
command assigns initial values to the parameters and signifies the
beginning of the model program. The model program specifies the nonlinear
equation that is chosen to model the data. There is no default model.
- The model program is required and must precede the
[C]NLR
command. - The
MODEL PROGRAM
command must specify all parameters in the model program. Each parameter must be individually named. KeywordTO
is not allowed. - Parameters can be assigned any acceptable variable
name. However, if you intend to write the final parameter estimates
to a file with the
OUTFILE
subcommand, do not use the name SSE or NCASES (see OUTFILE Subcommand (NLR command)). - Each parameter in the model program must have an
assigned value. The value can be specified on
MODEL PROGRAM
or read from an existing parameter data file named on theFILE
subcommand. - Zero should be avoided as an initial value because
it provides no information about the scale of the parameters. This
situation is especially true for
CNLR
. - The model program must include at least one command that uses the parameters and the independent variables (or preceding transformations of these) to calculate the predicted value of the dependent variable. This predicted value defines the nonlinear model. There is no default model.
- By default, the program assumes that PRED is the name assigned to the variable
for the predicted values. If you use a different variable name in
the model program, you must supply the name on the
PRED
subcommand (see PRED Subcommand (NLR command)). - In the model program, you can assign a label to the variable holding predicted values and also change its print and write formats, but you should not specify missing values for this variable.
- You can use any computational commands (such as
COMPUTE
,IF
,DO IF
,LOOP
,END LOOP
,END IF
,RECODE
, orCOUNT
) or output commands (WRITE
,PRINT
, orXSAVE
) in the model program, but you cannot use input commands (such asDATA LIST
,GET
,MATCH FILES
, orADD FILES
). - Transformations in the model program are used only
by
[C]NLR
, and they do not affect the active dataset. The parameters that are created by the model program do not become a part of the active dataset. Permanent transformations should be specified before the model program.