logistic回归class语句的param选项的说明如下:
PARAM=keyword specifies the parameterization method for the classification variable or variables. You can specify any of the keywords shown in the following table; the default is PARAM=EFFECT. Design matrix columns are created from CLASS variables according to the corresponding coding schemes:
Value of PARAM=
| Coding
|
EFFECT
| Effect coding
|
GLM
| Less-than-full-rank reference cell coding (this keyword can be used only in a global option)
|
ORDINAL
THERMOMETER
| Cumulative parameterization for an ordinal CLASS variable
|
POLYNOMIAL
POLY
| Polynomial coding
|
REFERENCE
REF
| Reference cell coding
|
ORTHEFFECT
| Orthogonalizes PARAM=EFFECT coding
|
ORTHORDINAL
ORTHOTHERM
| Orthogonalizes PARAM=ORDINAL coding
|
ORTHPOLY
| Orthogonalizes PARAM=POLYNOMIAL coding
|
ORTHREF
| Orthogonalizes PARAM=REFERENCE coding
|
All parameterizations are full rank, except for the GLM parameterization. The
REF= option in the CLASS statement determines the reference level for EFFECT and REFERENCE coding and for their orthogonal parameterizations. It also indirectly determines the reference level for a singular GLM parameterization through the order of levels.
If PARAM=ORTHPOLY or PARAM=POLY and the classification variable is numeric, then the
ORDER= option in the CLASS statement is ignored, and the internal unformatted values are used. See the section
Other Parameterizations of
Chapter 19: Shared Concepts and Topics, for further details.