[R] Post hoc analysis for ANOVA with repeated measures
Frodo Jedi
frodo.jedi at yahoo.com
Sun Jan 9 13:10:10 CET 2011
Dear all,
how can I perform a post hoc analysis for ANOVA with repeated measures (in
presence of a balanced design)?
I am not able to find a good example over internet in R...is there among you
someone so kind to give
me an hint with a R example please?
For example, the aov result of my analysis says that there is a statistical
difference between stimuli (there are 7 different stimuli).
...I would like to know which stimuli are involved.
> aov1 = aov(response ~ stimulus*condition + Error(subject/(stimulus*condition)),
>data=scrd)
> summary(aov1)
Error: subject
Df Sum Sq Mean Sq F value Pr(>F)
Residuals 14 227.57 16.255
Error: subject:stimulus
Df Sum Sq Mean Sq F value Pr(>F)
stimulus 6 11.695 1.94921 2.3009 0.04179 *
Residuals 84 71.162 0.84717
---
Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
Error: subject:condition
Df Sum Sq Mean Sq F value Pr(>F)
condition 1 42.076 42.076 12.403 0.003386 **
Residuals 14 47.495 3.393
---
Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
Error: subject:stimulus:condition
Df Sum Sq Mean Sq F value Pr(>F)
stimulus:condition 6 9.124 1.5206 1.4465 0.2068
Residuals 84 88.305 1.0513
>
In attachment you find the table I am using, you can access it by means of:
scrd<-
read.csv(file='/Users/....../tables_for_R/table_quality_gravel.csv',sep=',',header=T)
The data are from an experiment where participants had to evaluate on a seven
point likert scale
the realism of some stimuli, which are presented both in condition "A" and in
condition "AH".
Thanks in advance
Best regards
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