The SURVEYLOGISTIC Procedure
Response Variable Options
You specify the following options by enclosing them in parentheses after the response variable:

DESCENDING
DESC

reverses the order of response categories.
If both the DESCENDING and the ORDER= options are specified, PROC SURVEYLOGISTIC orders the response categories according to the ORDER= option and then reverses
that order. See the section Response Level Ordering for more detail.

EVENT=’category’  keyword

specifies the event category for the binary response model. PROC SURVEYLOGISTIC models the probability of the event category.
The EVENT= option has no effect when there are more than two response categories. You can specify the value (formatted if
a format is applied) of the event category in quotes or you can specify one of the following keywords. The default is EVENT=FIRST.
 FIRST

designates the first ordered category as the event
 LAST

designates the last ordered category as the event
One of the most common sets of response levels is {0,1}, with 1 representing the event for which the probability is to be
modeled. Consider the example where Y
takes the values 1 and 0 for event and nonevent, respectively, and Exposure
is the explanatory variable. To specify the value 1 as the event category, use the following MODEL statement:
model Y(event='1') = Exposure;

ORDER=DATA  FORMATTED  FREQ  INTERNAL

specifies the sort order for the levels of the response
variable. By default, ORDER=INTERNAL. For ORDER=FORMATTED and ORDER=INTERNAL, the sort order is machinedependent.
When the default ORDER=FORMATTED is in effect for numeric variables for which you have supplied no explicit format,
Value of ORDER=

Levels Sorted By

DATA

Order of appearance in the input data set

FORMATTED

External formatted value, except for numeric


variables with no explicit format, which are


sorted by their unformatted (internal) value

FREQ

Descending frequency count; levels with the


most observations come first in the order

INTERNAL

Unformatted value

For more information about sort order, see the chapter on the SORT procedure in the
Base SAS Procedures Guide and the discussion of BYgroup processing in
SAS Language Reference: Concepts.

REFERENCE=’category’  keyword
REF=’category’  keyword

specifies the reference category for the generalized logit model and the binary response model. For the generalized logit
model, each nonreference category is contrasted with the reference category. For the binary response model, specifying one
response category as the reference is the same as specifying the other response category as the event category. You can specify
the value (formatted if a format is applied) of the reference category in quotes or you can specify one of the following keywords. The default is REF=LAST.
 FIRST

designates the first ordered category as the reference
 LAST

designates the last ordered category as the reference
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