Dear R users,I am looking for an easy (i.e., direct) way in obtaining the F and
p values from the intercept in anovas with within-subject designs. Data are
from a psychophysics expeirment where I am using d' (d-prime) values obtained
from 3 modalities of presentation in each subject.I would like to know not only
whether there is an effect of modality, but also wether the main effect is
signiticant (meaning that d' is differnt from 0). I know that a t.test again
the nul mean would provide me with similar stats on the main effect, but I
would like to get those stats in an F form, for consistency with the stats on
the other factors of interest.
As far as I understand how R works, the function "anova" provides you with such
information but it is restricted to between-group analyses. For within-subject
designs, one has to use summray(aov) but stats on the intercept are not
included in the the result of this function. I have pasted an exemple below. As
onc can see only the Sum of Sq and Mean Sq are given from the main effect.Thank
you for any advice you can provide,-Sid> summary(aov(x~mod+Error(suj/(mod)),
data=dp))Error: suj Df Sum Sq Mean Sq F value Pr(>F)Residuals 10
19.5977 1.9598 Error: suj:mod Df Sum Sq Mean Sq F
value Pr(>F) mod 2 8.2475 4.1237 4.2955 0.02806 *Residuals 20
19.2005 0.9600 ---Signif. codes: 0 '***' 0.001 '**' 0.01 '*'
0.05 '.' 0.1 ' ' 1 Error: Within Df Sum Sq Mean Sq F value
Pr(>F)Residuals 33 55.812 1.691
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tiative now. Its free.
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