Asking, are simple effects different from 0

Ah.  I see.  So, if I want to test to see whether each simple effect is
different from 0, I would do something like the following:


cm2 <- rbind( 
"A:L" =  c(1, 0, 0, 0, 0, 0), 
"A:M" = c(1, 1, 0, 0, 0, 0), 
"A:H" = c(1, 0, 1, 0, 0, 0), 
"B:L" =   c(1, 0, 0, 1, 0, 0), 
"B:M" = c(1, 1, 0, 1, 1, 0), 
"B:H" = c(1, 0, 1, 1, 0, 1))

summary(glht(fm, linfct = cm2), test = adjusted(type="none")) 

Correct? What is the df on those t-tests then?  Is it 48?

Interestingly, I find this produces results no different than

fm2<-lm(breaks ~ tension:wool+0, data=warpbreaks) 
summary(fm2)

Also, here, it would seem each t-test was done with the full 48df.  Hrm.

   Each column corresponds to one of the coefficients in the model, and 
each row specifies a particular contrast.  The numbers in the matrix 
indicate how the model coefficients are combined to indicate a 
particular difference in means.
   For example, the first row indicates that the third coefficient 
(woolB) is multiplied by -1.  The baseline categories are A and L for 
the wool and tension factors, so the woolB effect in fm is the simple 
effect of B vs. A in the baseline category of the tension factor. 
Multiplying this coefficient by -1 produces an A vs. B comparison in the 
baseline category of the tension factor.
 

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