Two things:
1. the + Sex term is superfluous
2. the variable Subject needs to be a Factor, not a vector (as I
suspect it currently is). That is, add:
mydata.tab$Subject=as.factor(mydata.tab$Subject)
in the preamble before the aov call, and all should be fine.
On 29-Apr-08, at 4:00 AM, [EMAIL PROTECTED] wrote:
Hi Folks,
I have repeated measures for data on association time (under 2
acoustic condtions) in male and female frogs as they grow to adulthood
(6 timepoints). Thus, two within-subject variables (Acoustic
Condition: 2 levels, Timepoint: 6 levels) and one between-subject
variable (Sex:male or female).
I am pretty sure my distributions depart from normality but I would
first like to simply run a RM anova on the data. My problem is that
when I do this I generate different values of F for my main effects
and interaction when I do the analysis in [R] and SPSS - so I don't
know which one to believe.
Here is my code in R:
mydata.tab=read.delim("mydata.txt", header=T) #read in my data
mydata.tab$Timepoint=as.factor(mydata.tab$Timepoint) #col headings
are factors so df are correct
mydata.tab$Acx.Cond=as.factor(mydata.tab$Acx.Cond)
mydata.tab$Sex=as.factor(mydata.tab$Sex)
aov.F=aov(Targ.Assoc.Time~(Timepoint*Acx.Cond*Sex) + Error(Subject/
(Timepoint*Acx.Cond))+(Sex), data=mydata.tab)
#run aov where i look at the main effects of Timepoint, Acoustic
Condition and Sex as well as all the interactions therein on the
amount of time a frog spends associating with the target sound.
Include anything to do with Subject in the error term.
Does this look right for a Repeated Measures ANOVA, or am I missing
something to make it RM and that explains the large discrepancies in
my F-values between [R] and SPSS?
As soon as I get this canonical aov code figured out I want to derive
my p-values by bootstrapping my F distributions, but first I need
those canonical F's.
Thanks
-Alex
--
Alexander T Baugh
Section of Integrative Biology
Univ. of Texas at Austin C0930
Austin, TX 78712
http://darktropic.blogspot.com/
--
Please avoid sending me Word or PowerPoint attachments.
See <http://www.gnu.org/philosophy/no-word-attachments.html>
-Dr. John R. Vokey
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