Hello everyone,
i have a question regarding the sampling process in boot().
I try to bootstrap F-values for a repeated measures ANOVA to get a confidence
interval of F-values. Unfortunately, while the aov works fine, it fails in the
boot()-function. I think the problem might be that the resampling process fails
to select both lines of data representing the 2 measuring times for one subject
and I therefore get missing cases.
The data is organised like this:
subject ort mz PHQ
1 1 1 x
1 1 2 y
2 1 1 z
2 1 2 zz
...
Is there any way to specify, that both lines need to be selected?
Thanks a lot!
Felix Fischer
P.S. If you need to have a look to my code:
F_values <- function(formula, data, indices) {
d <- data[indices,] # allows boot to select sample
fit=aov(formula,data=d) #fit model
return(c(summary(fit)[1][[1]][[1]]$`F value`, summary(fit)[2][[1]][[1]]$`F
value`)) #return F-values
}
results <- boot(data=anova.daten, statistic=F_values,
R=10, formula=PHQ_Sum_score~mz*ort+Error(subject/mz))
Dipl. Psych. Felix Fischer
Medizinische Klinik mit Schwerpunkt Psychosomatik
Charité -- Universitätsmedizin Berlin
Luisenstr. 13a
10117 Berlin
Tel.: 030 - 450 553575
Email: [email protected]<mailto:[email protected]>
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