[R] how to assign fixed factor in lm

[genomenet at gmail.com]

Hi there,

> Value=c(709,679,699,657,594,677,592,538,476,508,505,539)
> Lard=rep(c("Fresh","Rancid"),each=6)
> Gender=rep(c("Male","Male","Male","Female","Female","Female"),2)
> Food=data.frame(Value,Lard,Gender)
> Food
   Value   Lard Gender
1    709  Fresh   Male
2    679  Fresh   Male
3    699  Fresh   Male
4    657  Fresh Female
5    594  Fresh Female
6    677  Fresh Female
7    592 Rancid   Male
8    538 Rancid   Male
9    476 Rancid   Male
10   508 Rancid Female
11   505 Rancid Female
12   539 Rancid Female
> lm(fixed=Value~Gender,data=Food)
Call:
lm(data = Food, fixed = Value ~ Gender)

Coefficients:
(Intercept)   LardRancid   GenderMale  
      651.4       -142.8         35.5  

Warning message:
extra arguments fixed are just disregarded. in: lm.fit(x, y, offset = offset, singular.ok = singular.ok, ...) 

> lm(fixed=Value~Lard+Gender,data=Food)

Call:
lm(data = Food, fixed = Value ~ Lard + Gender)

Coefficients:
(Intercept)   LardRancid   GenderMale  
      651.4       -142.8         35.5  

Warning message:
extra arguments fixed are just disregarded. in: lm.fit(x, y, offset = offset, singular.ok = singular.ok, ...) 

I wanted to consider only one factor. But why lm(fixed=Value~Gender,data=Food)
return me two estimates of Gender and Lard. And I found the returning
results are the same as lm(fixed=Value~Lard+Gender,data=Food). Why lm
cannot do analysis of variance according to assigned formula?

Thank you very much.

Fan