我想用Generalized Linear Models 做回归分析，例如附图中的变量treatment有两种情况{t1, t2}，另外一个变量duration也有两种情况{d1, d2}。在treatment的每种情况下，都存在duration的两种情况。为了分析duration在不同treatment条件下对结果的影响，定义model的时候，我应该build nested term，对吧?


那么我怎么在SPSS的model中如何表达呢？到底时duration(treatment)还是treatment(duration)?

IBM SPSS Advanced Statistics 21 提供的文档第55页是这么说的，但是不太明白。

Nested Terms
You can build nested terms for your model in this procedure. Nested terms are useful for modeling
the effect of a factor or covariate whose values do not interact with the levels of another factor.
For example, a grocery store chain may follow the spending habits of its customers at several store
locations. Since each customer frequents only one of these locations, the Customer effect can be
said to be nested within the Store location effect.

另外，我发现改变model中变量的顺序，结果发生很大的变化。请问这样正常吗？是什么原因造成的？

谢谢！！！

－－－因为不懂如何附图，随便发了后删除不掉，请忽略下面的图片。