PLS Syntax - Overview

The PLS syntax consists of command lines, which are terminated by semicolons. The complete command syntax for PLS is shown below. Note that terms in curly brackets ({}) denote alternate specifications (e.g., INTERCEPT = INCLUDE or INTERCEPT = EXCLUDE); optional keywords are enclosed in brackets ([]); all keywords are shown in upper case letters (even thought the syntax interpreter is not case sensitive).

PLS and GLM syntax conventions
The PLS syntax conventions are essentially identical to the GLM syntax conventions (see General Linear Models (GLM), with only a few additions and omissions. Most notable, mixture designs and repeated measures designs cannot be analyzed in PLS. The following is a list of keywords available in PLS; note that the Generalized Linear/Nonlinear Model (GLZ) and General Regression Models (GRM) modules also use similar syntax, with sets of additional keywords (options) that are specific to those particular applications. To learn more about each keyword, click on it.

[PLS;]

DEPENDENT [=] { Variable List };
[GROUPS [=] { NONE };
    { Variable [(Value List)
    .......
    Variable [(Value List)] };]
[COVARIATE [=] { NONE };
    { Variable List };]
[DESIGN [=] { NONE };
    { Effects };]
[INTERCEPT [=] { EXCLUDE }
    { INCLUDE };]
[EDELTA [=] { Value };]
[RDELTA [=] { Value };]
[SURFACE [=] [=] { NONE }
    { Covariate Variable List };]
[MAXITER [=] Value;]
[NCOMPO [=] Value;]
[AUTOSCALE [=] { YES }
    { NO };]
[METHOD [=] { PLS }
    { SIMPLS }]
[SAMPLE [=] { NONE }
    { Variable (Value) };]
[OUTPUT [=] { NONE }
    { List of options (integers) };]
Example
Shown below is an example specification for a partial least squares analysis that includes two categorical predictors and their interaction, as well as continuous predictor variables (use example datafile Exp.sta to run this examples).

PLS

DEPENDENT = STRESS_R;
GROUPS = GROUP GENDER;
COVARIATE = CORRECT1 CORRECT2 CORRECT3;
DESIGN = CORRECT1+CORRECT2+CORRECT3 + GROUP | GENDER;
INTERCEPT = EXCLUDE;
PARAM = SIGMA;
EDELTA = 12;
RDELTA = 12;
MAXITER = 200;
NCOMPO = 120;
AUTOSCALE = YES;
METHOD = PLS;

For more examples, see the PLS Syntax Examples.

Upper case and lower case letters
The syntax editor is not case sensitive; i.e., DEPENDENT and dependent or Dependent are all valid specifications of the same keyword.
Order of keywords
The order of keywords should follow that implied in the complete listing of all keywords shown above. Note that, while most of the options can be specified in any order, the Design statement must follow the Dependent, Groups, and Covariate specifications. In general, when a keyword references a variable or effect previously defined, then that specification must occur before the respective keyword reference.
Comments
You can insert comments into the syntax by placing them in curly brackets (e.g., { This is a comment }), or after a pound sign (e.g., ... # This is a comment; all text starting at the pound sign to the end of the respective line will be treated as a comment). You may place comments in between any keywords of the syntax, and you may include several comment lines. Comments will be ignored when the syntax is parsed.