[R] (no subject)

Greg Snow Greg.Snow at intermountainmail.org
Thu Aug 30 21:43:19 CEST 2007

Try calling summary.lm on your object (if it is an aov object then summary calls summary.aov which does not show the intercept, but calling summary.lm directly does give info on the intercept).

Gregory (Greg) L. Snow Ph.D.
Statistical Data Center
Intermountain Healthcare
greg.snow at intermountainmail.org
(801) 408-8111

> -----Original Message-----
> From: r-help-bounces at stat.math.ethz.ch 
> [mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of Sid Kouider
> Sent: Thursday, August 30, 2007 4:33 AM
> To: r-help at stat.math.ethz.ch
> Subject: [R] (no subject)
> 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               
> _________________________________________________________________
> tiative now. It's free. 
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