[R] Anova and covariable
john polo
jpolo at mail.usf.edu
Tue Nov 24 22:49:12 CET 2009
Dear R users,
i want to use ANOVA with a small data set, here is an example of the data:
Rich FireDe TimeS Area
8 2 4 C
9 2.5 7 C
5 1.9 2 C
7 3 4 C
8 2.5 0 L
2 4 3 L
9 2.5 6 L
9 3 6 L
10 1.5 2 O
3 3.5 9 O
7 2 7 O
5 2.5 4 O
in a randomized block design, where the Areas are supposed to be the blocks,
i want to test the null hypothesis for Rich and FireDe by itself or with
TimeS. i would like to control for the Area, use it as a covariable i guess,
but don't know how to with this:
summary(lm(Rich~FireDe _ Area ))
or
summary(lm(Rich~FireDe _ TimeS _ Area))
in the places i've looked, i've seen * and + used where i typed "_", but i
wasn't sure if it was for a one-way or two-way Anova or a covariate.
best regards,
john polo
G.R.A.
OK State
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