r - Sum of squares are different for the same factor -
i executing anova model data , observed sum of squares (and mean squares, resp.) 1 of effects not equal in 1-way anova , 2-way anova.
# df sum sq mean sq f value pr(>f) # b 2 18.1 9.047 0.736 0.485 # residuals 44 540.5 12.285 summary(aov(x~a,dat)) # df sum sq mean sq f value pr(>f) # 1 1.0 1.001 0.081 0.778 # residuals 45 557.6 12.392 summary(aov(x~a+b,dat)) # df sum sq mean sq f value pr(>f) # 1 1.0 1.001 0.080 0.779 # **b 2 20.1 10.027 0.802 0.455** # residuals 43 537.6 12.502 summary(aov(x~a*b,dat)) # df sum sq mean sq f value pr(>f) # 1 1.0 1.00 0.113 0.738815 # **b 2 20.1 10.03 1.129 0.333084** # a:b 2 173.6 86.78 9.773 0.000338 *** # residuals 41 364.0 8.88
as see b effect sum sq not equal throughout different anova models.
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