Two Different Interaction Terms for Mixed Factorial ANOVA in R?
Angela, My guess is that your data are not balanced. That could be due to a typo in one of the factors, or it could be that you actually have different numbers of observations at some of the factor levels. Rich On Sun, May 17, 2015 at 12:05 PM, Angela Radulescu
<angela.radulescu at gmail.com> wrote:
I have the following R output from a mixed factorial ANOVA:
Error: subj
Df Sum Sq Mean Sq F value Pr(>F) group
1 11.3 11.26 0.449 0.50811
singleType 1 0.7 0.66 0.026 0.87220 group:singleType
1 237.5 237.53 9.484 0.00461 **Residuals 28 701.3 25.04
---Signif. codes: 0 ?***? 0.001 ?**? 0.01 ?*? 0.05
?.? 0.1 ? ? 1
Error: subj:singleType
Df Sum Sq Mean Sq F value Pr(>F)
singleType 1 1566.4 1566.4 411.445 <2e-16 ***group:singleType
1 3.4 3.4 0.893 0.352 Residuals 30 114.2 3.8
---Signif. codes: 0 ?***? 0.001 ?**? 0.01 ?*? 0.05
?.? 0.1 ? ? 1
Error: Within
Df Sum Sq Mean Sq F value Pr(>F)Residuals 3286 5747 1.749
Here "group" is the between factor (2 levels) and "singleType" the within
factor (2 levels). I'm not sure why there are two group:singleType
interaction terms. Any help would be much appreciated!
For reference, here is the original aov call:
anova.p = aov(data = dat.colSingle, rt ~ (group*singleType) +
Error(subj/singleType))
summary(anova.p)
Thank you!
--
Angela Radulescu
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