Tanks are the experimental unit, fishes within tanks are repeated measures
of the treatment, there is no "nesting" of replicates. You can analyze the
45 x 50 individual data values by repeated measures (mixed effects models)
or by summarizing the 50 measurements per tank=treatment into a single value
and then doing exactly what Indrajit said with the 45 summarized values.

-- Bert

On Mon, Sep 26, 2011 at 10:27 PM, Austin Paul <austinpa@usc.edu> wrote:

> Hi,
>
> Yes.  As I explained, the three male and three female types were crossed in
> all combinations (9 ways).  For each of the 9 types, I have *5 replicate
> tanks* (45 total tanks).  And from each of the 45 tanks I have 50
> observations for size.  So the 5 replicates are somehow nested within the
> two-way interaction?  If there was just 1 tank for each of the 9 crosses,
> yes, it would be very easy to code the two-way anova.  It may still be very
> easy, but I'm not quite sure how to account for the replicate tanks.
>
> Hope this makes more sense.
>
> Austin
>
>
>
> On Mon, Sep 26, 2011 at 10:21 PM, Indrajit Sengupta <
> indra_calisto@yahoo.com
> > wrote:
>
> > Can you explain what do you mean by "5 replicate tanks"?
> >
> > Doing a two way anova is very simple in R. You would need to fit a linear
> > model (lm function).
> >
> > Eg.:
> >
> > > model <- lm(y ~ male + female + male:female, data =)
> >
> >
> > Regards,
> > Indrajit
> >
> >
> > ------------------------------
> > *From:* Austin Paul <austinpa@usc.edu>
> > *To:* r-help@r-project.org
> > *Sent:* Tuesday, September 27, 2011 6:13 AM
> > *Subject:* [R] two-way anova help
> >
> > Hello,
> >
> > I am having some trouble coding a two-way anova due to replicated
> > treatments.
> >
> > I have a factorial design with three male parents and three female
> parents.
> > They were mated in all combinations and their babies were grown out and
> > measured for size.  50 babies were measured for each of the 9 crosses.
>  If
> > I
> > stopped here, I would have no troubles.  But I also have 5 replicate
> tanks
> > for each of the 9 crosses.  My question is how to I code in the 5
> replicate
> > tanks per treatment?
> >
> > Thanks,
> > Austin
> >
> >     [[alternative HTML version deleted]]
> >
> > ______________________________________________
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> > PLEASE do read the posting guide
> > http://www.R-project.org/posting-guide.html
> > and provide commented, minimal, self-contained, reproducible code.
> >
> >
> >
>
>        [[alternative HTML version deleted]]
>
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