[R] Estimated Effects Not Balanced

Bert Gunter bgunter.4567 at gmail.com
Mon Aug 22 17:27:11 CEST 2016


"when I compute the anova R reports
that the Estimated Effects are Unbalanced"

It does *not* say this. It says that they **may** be unbalanced. They are not.

-- Bert
Bert Gunter

"The trouble with having an open mind is that people keep coming along
and sticking things into it."
-- Opus (aka Berkeley Breathed in his "Bloom County" comic strip )

On Mon, Aug 22, 2016 at 8:15 AM, Justin Thong <justinthong93 at gmail.com> wrote:
> Something does not make sense in R. It has to do with the question of
> balance and unbalance.
> *A<-factor(c(1,1,1,1,1,1,2,2,2,2,2,2))*
> *B<-factor(c(1,1,2,2,3,3,1,1,2,2,3,3))*
> *y<-rnorm(12)*
> *mod<-aov(y~A+B)*
> I was under the impression that the design is balanced ie order does not
> effect the sums of squares. However, when I compute the anova R reports
> that the Estimated Effects are Unbalanced. I thought that when all
> combinations of levels of A and B have equal replications then the design
> is called balanced. But, R tends to think that when not all levels of A and
> levels of B have equal replication, then the "Estimated Effects are
> unbalanced".... Is this the same as the design being unbalanced? Because
> for the example below, where the error occured, the order does not matter
> (which make me think that the design is balanced).
> *Call:*
> *   aov(formula = y ~ A + B)*
> *Terms:*
> *                        A         B Residuals*
> *Sum of Squares   0.872572  0.025604 16.805706*
> *Deg. of Freedom         1         2        10*
> *Residual standard error: 1.296368*
> *Estimated effects may be unbalanced*
> --
> Yours sincerely,
> Justin
> *I check my email at 9AM and 4PM everyday*
> *If you have an EMERGENCY, contact me at +447938674419(UK) or
> +60125056192(Malaysia)*
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