Example 4 for PROC LOGISTIC
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/* S A S S A M P L E L I B R A R Y */
/* */
/* NAME: LOGIEX4 */
/* TITLE: Example 4 for PROC LOGISTIC */
/* PRODUCT: STAT */
/* SYSTEM: ALL */
/* KEYS: logistic regression analysis, */
/* polytomous response data */
/* PROCS: LOGISTIC */
/* DATA: */
/* */
/* SUPPORT: Bob Derr */
/* REF: SAS/STAT User's Guide, PROC LOGISTIC chapter */
/* MISC: */
/* */
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Example 4. Nominal Response Data: Generalized Logits Model
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/*
Stokes, Davis, and Koch (2000). Over the course of one school year, third
graders from three different schools are exposed to three different styles of
mathematics instruction: a self-paced computer-learning style, a team
approach, and a traditional class approach. The students are asked which
style they prefer and their responses are classified by the type of program
they are in (a regular school day versus a regular day supplemented with an
afternoon school program). The levels (self, team, and class) of the
response variable Style have no essential ordering, so a logistic regression
is performed on the generalized logits. An interaction model then a main
effects model are fit.
*/
title 'Example 4. Nominal Response Data: Generalized Logits Model';
data school;
length Program $ 9;
input School Program $ Style $ Count @@;
datalines;
1 regular self 10 1 regular team 17 1 regular class 26
1 afternoon self 5 1 afternoon team 12 1 afternoon class 50
2 regular self 21 2 regular team 17 2 regular class 26
2 afternoon self 16 2 afternoon team 12 2 afternoon class 36
3 regular self 15 3 regular team 15 3 regular class 16
3 afternoon self 12 3 afternoon team 12 3 afternoon class 20
;
ods graphics on;
proc logistic data=school;
freq Count;
class School Program(ref=first);
model Style(order=data)=School Program School*Program / link=glogit;
oddsratio program;
run;
proc logistic data=school;
freq Count;
class School Program(ref=first);
model Style(order=data)=School Program / link=glogit;
effectplot interaction(plotby=Program) / clm noobs;
run;