[Rd] aov for unbalanced design (PR#7144)

From: <tlogvinenko_at_partners.org>
Date: Fri 30 Jul 2004 - 06:43:20 EST


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 ______________________________________________ R-devel@stat.math.ethz.ch mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-devel
Received on Fri Jul 30 06:47:22 2004

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