PROC GENMOD Statement

PROC GENMOD < options > ;

DATA=SAS-data-set

specifies the SAS data set containing the data to be analyzed. If you omit the DATA= option, the procedure uses the most recently created SAS data set.

DESCENDING | DESC

specifies that the levels of the response variable for the ordinal multinomial model be sorted in the reverse of the default order. For example, if RORDER=FORMATTED (the default), the DESCENDING option causes the levels to be sorted from highest to lowest instead of from lowest to highest. If RORDER=FREQ, the DESCENDING option causes the levels to be sorted from lowest frequency count to highest instead of from highest to lowest.

NAMELEN=n

specifies the length of effect names in tables and output data sets to be n characters long, where n is a value between 20 and 200 characters. The default length is 20 characters.

ORDER=keyword

specifies the sorting order for the levels of the classification variables (specified in the CLASS statement). This ordering determines which parameters in the model correspond to each level in the data, so the ORDER= option may be useful when you use the CONTRAST or ESTIMATE statement. Note that the ORDER= option applies to the levels for all classification variables. The exception is ORDER=FORMATTED (the default) for numeric variables for which you have supplied no explicit format (that is, for which there is no corresponding FORMAT statement in the current PROC GENMOD run or in the DATA step that created the data set). In this case, the levels are ordered by their internal (numeric) value. Note that this represents a change from previous releases for how class levels are ordered. In releases previous to Version 8, numeric class levels with no explicit format were ordered by their BEST12. formatted values, and in order to revert to the previous ordering you can specify this format explicitly for the affected classification variables. The change was implemented because the former default behavior for ORDER=FORMATTED often resulted in levels not being ordered numerically and usually required the user to intervene with an explicit format or ORDER=INTERNAL to get the more natural ordering. The following table displays the valid keywords and describes how PROC GENMOD interprets them.

ORDER= keyword	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

By default, ORDER=FORMATTED. For ORDER=FORMATTED and ORDER=INTERNAL, the sort order is machine dependent. For more information on sorting order, refer to the chapter titled "The SORT Procedure" in the SAS Procedures Guide.

RORDER=keyword

specifies the sorting order for the levels of the response variable. This ordering determines which intercept parameter in the model corresponds to each level in the data. If RORDER=FORMATTED (the default) for numeric variables for which you have supplied no explicit format (that is, for which there is no corresponding FORMAT statement in the current PROC GENMOD run or in the DATA step that created the data set), the levels are ordered by their internal (numeric) value. Note that this represents a change from previous releases for how class levels are ordered. In releases previous to Version 8, numeric class levels with no explicit format were ordered by their BEST12. formatted values, and in order to revert to the previous ordering you can specify this format explicitly for the response variable. The change was implemented because the former default behavior for RORDER=FORMATTED often resulted in levels not being ordered numerically and usually required the user to intervene with an explicit format or RORDER=INTERNAL to get the more natural ordering. The following table displays the valid keywords and describes how PROC GENMOD interprets them.

RORDER= keyword	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

By default, RORDER=FORMATTED. For RORDER=FORMATTED and RORDER=INTERNAL, the sort order is machine dependent. The DESCENDING option in the PROC GENMOD statement causes the response variable to be sorted in the reverse of the order displayed in the previous table. For more information on sorting order, refer to the chapter on the SORT procedure in the SAS Procedures Guide.

The NOPRINT option, which suppresses displayed output in other SAS procedures, is not available in the PROC GENMOD statement. However, you can use the Output Delivery System (ODS) to suppress all displayed output, store all output on disk for further analysis, or create SAS data sets from selected output. You can suppress all displayed output with the statement ODS SELECT NONE;, and you can turn displayed output back on with the statement ODS SELECT ALL;. See Table 29.3 for the names of output tables available from PROC GENMOD. For more information on ODS, see Chapter 15, "Using the Output Delivery System."