[R] Can I treat subject as fixed effect in linear model

[shirley zhang]

Hi,

There are 20 subjects grouped by Gender, each subject has 2 tissues
(normal vs. cancer).

In fact, it is a 2-way anova (factors: Gender and tissue) with tissue
nested in subject. I've tried the following:

Model 1: lme(response ~ tissue*Gender, random = ~1|subject)
Model 2: response ~ tissue*Gender + subject
Model 3: response ~ tissue*Gender


It seems like Model 1 is the correct one since my experiment design is
nested design. However, can anybody tell me whether Model2 is
completely illegal?

Thanks