[Rd] aov for unbalanced design (PR#7144)
tlogvinenko at partners.org
tlogvinenko at partners.org
Thu Jul 29 22:43:20 CEST 2004
Full_Name: Tanya Logvinenko
Version: 1.7.0
OS: Windows 2000
Submission from: (NULL) (132.183.156.125)
For unbalanced design, I ran into problem with ANOVA (aov function). The sum of
squares for only for the second factor and total are computed correctly, but sum
of squares for the first factor is computed incorreclty. Changing order of
factors in the formula changes the ANOVA table. For the balanced design, there
is no such problem.
> summary(aov(data[1,]~factor1+factor2))
Df Sum Sq Mean Sq F value Pr(>F)
factor1 5 1524420 304884 6.4529 0.0003229 ***
factor2 7 1447830 206833 4.3776 0.0017808 **
Residuals 31 1464674 47248
---
Signif. codes: 0 `***' 0.001 `**' 0.01 `*' 0.05 `.' 0.1 ` ' 1
> summary(aov(data[1,]~factor2+factor1))
Df Sum Sq Mean Sq F value Pr(>F)
factor2 7 1648225 235461 4.9836 0.0007295 ***
factor1 5 1324025 264805 5.6046 0.0008612 ***
Residuals 31 1464674 47248
---
Signif. codes: 0 `***' 0.001 `**' 0.01 `*' 0.05 `.' 0.1 ` ' 1
More information about the R-devel
mailing list