[R] model reparameterization

[casperyc]

==================================
y=c(100,200,300,400,500)
treatment=c(1,2,3,3,4)
block=c(1,1,2,3,3)

summary(lm(y~as.factor(treatment)+as.factor(block)))
==================================

The aim is to find a model that can estimate
the comparison between treatment 1 with 2
and treatment 3 with 4.

I have tried all the possible ones
===========================================
relevel(as.factor(block),ref="1");relevel(as.factor(treatment),ref="1")
relevel(as.factor(block),ref="1");relevel(as.factor(treatment),ref="2")
relevel(as.factor(block),ref="1");relevel(as.factor(treatment),ref="3")
relevel(as.factor(block),ref="1");relevel(as.factor(treatment),ref="4")

relevel(as.factor(block),ref="2");relevel(as.factor(treatment),ref="1")
relevel(as.factor(block),ref="2");relevel(as.factor(treatment),ref="2")
relevel(as.factor(block),ref="2");relevel(as.factor(treatment),ref="3")
relevel(as.factor(block),ref="2");relevel(as.factor(treatment),ref="4")

relevel(as.factor(block),ref="3");relevel(as.factor(treatment),ref="1")
relevel(as.factor(block),ref="3");relevel(as.factor(treatment),ref="2")
relevel(as.factor(block),ref="3");relevel(as.factor(treatment),ref="3")
relevel(as.factor(block),ref="3");relevel(as.factor(treatment),ref="4")
============================================

each followed by a line of

summary(lm(y~as.factor(treatment)+as.factor(block)))

i seem to always get "NaN"s

Am I doing something wrong there?

What model should I use then?

Thanks!

casper

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