Re: [R] factorial anova

From: Rick Bilonick <rab_at_nauticom.net>
Date: Mon 26 Dec 2005 - 13:09:55 EST

On Sun, 2005-12-25 at 23:01 -0300, Petra Wallem wrote:
> Hello every body, I am trying to do a factorial anova analysis
> following this model:
>
> model<-anova(lm(responsevariable~factorA*factorB))
> model<-anova(lm(luz$dosel~luz$estado*luz$Bosque))
>
> Df Sum Sq Mean Sq F value Pr(>F)
> estado 1 6931.1 6931.1 41.6455 7.974e-06 ***
> Bosque 1 36.6 36.6 0.2197 0.6456
> estado:Bosque 1 36.6 36.6 0.2197 0.6456
> Residuals 16 2662.9 166.4
>
> Strange is that the sum of squares of the factor Bosque are identical to
> the SS of the interaction, and are non significant. But when I plot the
> data, the interaction surley is significant...
>
> my data.frame looks as follows:
>
> Bosque estado lux dosel
> 1 deciduo pristino 703 88.56
> 2 deciduo pristino 800 90.64
> 3 deciduo pristino 150 95.84
> 4 deciduo pristino 245 87.52
> 5 deciduo pristino 1300 91.68
> 6 deciduo activo 1900 26.16
> 7 deciduo activo 840 59.44
> 8 deciduo activo 323 69.84
> 9 deciduo activo 112 75.04
> 10 deciduo activo 1360 51.12
> 11 siemprev activo 900 41.76
> 12 siemprev activo 480 65.68
> 13 siemprev activo 350 78.16
> 14 siemprev activo 350 37.60
> 15 siemprev activo 272 58.40
> 16 siemprev pristino 100 94.80
> 17 siemprev pristino 60 95.84
> 18 siemprev pristino 50 97.92
> 19 siemprev pristino 270 94.80
> 20 siemprev pristino 110 97.92
>
> Dose some body understand what I am doing wrong??? I have been
> navigating at the R site search, but didn't found much posting on
> factorial anova.
>
> In advance thanks a lot for your comments
> Petra
>
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> PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html

It would help if you would use the "dump" function and paste the output into an e-mail:

> dump("luz","")

Also, it's much easier to use "data=luz" as an argument in the lm function rather than appending the data frame name to each variable. I don't think that "model" contains the lm model output. It looks like you are saving the anova table.



R-help@stat.math.ethz.ch mailing list
https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html Received on Mon Dec 26 13:17:07 2005

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