我在做clogit的过程中遇到一个问题,
无约束模型:clogit y x1 x2 x3 x4,group(id)
那么该如何做约束模型(constraint model)
我的尝试
constraint define 1 x1=0
constraint define 2 x2=0
constraint define 3 x3=0
constraint define 4 x4=0
clogit y x1 x2 x3 x4, group(id) constraint(1-4)
结果显示
note: multiple positive outcomes within groups encountered.
note: 1 group (21 obs) dropped due to all positive or
all negative outcomes.
there are at least as many constraints as parameters
不怎么理解上面的意思,请帮忙看一下。3x