[R] Fisher's LSD multiple comparisons in a two-way ANOVA

[Jinsong Zhao]

Hi there,

Is there a function that can do a Fisher's LSD multiple comparisons in a 
two-way ANOVA? I hope to get a result similar with TukeyHSD(). 
Especially, I hope to know the significance of comparisons between the 
interactions of two factors.

In the following example:

x <- c(76, 84, 78, 80, 82, 70, 62, 72, 71, 69, 72, 74, 66, 74, 68, 66, 
69, 72, 72, 78, 74, 71, 73, 67, 86, 67, 72, 85, 87, 74, 83, 86, 66, 68, 
70, 76, 78, 76, 69, 74, 72, 72, 76, 69, 69, 82, 79, 81)
a <- rep(c("A1","A2"), each = 24)
b <- rep(c("B1","B2","B3"), each =8, times = 2)
a <- factor(a)
b <- factor(b)
x.aov <- aov(x~a*b)

I hope to obtained the results similar with"

http://www.gigawiz.com/images12/twowayrmposthoc.jpg

Any suggestions or comments will be really appreciated.

Regards,
Jinsong