Probability for ANOVA
Laurent Houdusse <l.houdusse at cerep.fr> writes:
Hi all!
I have 4 treatments on 5 animals
Treat1 Treat2 Treat3 Treat4
Animal1 36 37 35 39
Animal2 33 34 36 37
Animal3 37 35 33 38
Animal4 34 36 34 35
Animal5 35 36 33 36
I use an Anova and i try to verify calcul
So i retrieve:
DF SS MS F P
Between Groups 3 20.950 6.983 3.492
Residual 16 32.000 2.000
Total 19 52.950 2.787
How can i calcul the p-Value? Is there a function to do this?
Yes:
1-pf(3.492,3,16)
[1] 0.04032243 However, this might not be the appropriate analysis if the animals are the same across treatments (not that it matters much in this case):
summary(aov(y ~ treat, data=dd))
Df Sum Sq Mean Sq F value Pr(>F) treat 3 20.950 6.983 3.4917 0.04033 * Residuals 16 32.000 2.000 --- Signif. codes: 0 `***' 0.001 `**' 0.01 `*' 0.05 `.' 0.1 ` ' 1
summary(aov(y ~ treat+animal, data=dd))
Df Sum Sq Mean Sq F value Pr(>F) treat 3 20.9500 6.9833 3.9343 0.03623 * animal 4 10.7000 2.6750 1.5070 0.26146 Residuals 12 21.3000 1.7750 --- Signif. codes: 0 `***' 0.001 `**' 0.01 `*' 0.05 `.' 0.1 ` ' 1
O__ ---- Peter Dalgaard Blegdamsvej 3 c/ /'_ --- Dept. of Biostatistics 2200 Cph. N (*) \(*) -- University of Copenhagen Denmark Ph: (+45) 35327918 ~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk) FAX: (+45) 35327907