Hi everyone,
I'm trying to do a 2-way repeated measures ANOVA with data that looks like
this:
subject block rep day light response
1 1 1 one L1 5.5
2 1 2 one L1 4.5
3 1 1 one L2 4
4 1 2 one L2 5.1
5 2 1 one L1 5.3
6 2 2 one L1 4.8
7 2 1 one L2 4.6
8 2 2 one L2 4.9
1 1 1 two L1 5.2
2 1 2 two L1 5.0
3 1 1 two L2 3.2
4 1 2 two L2 3.4
5 2 1 two L1 4.6
6 2 2 two L1 4.9
7 2 1 two L2 3.3
8 2 2 two L2 2.9
I'm using lme():
m1<-light(buoy~light*day, random=~1|subject/day)
summary(m1)
and get this output:
Linear mixed-effects model fit by REML
Data: NULL
AIC BIC logLik
24.94574 28.34008 -5.472868
Random effects:
Formula: ~1 | subject
(Intercept)
StdDev: 0.05400619
Formula: ~1 | day %in% subject
(Intercept) Residual
StdDev: 0.2912773 0.06415494
Fixed effects: response ~ light * day
Value Std.Error DF t-value p-value
(Intercept) 5.025 0.1515545 6 33.15640 0.0000
lightL2 -0.200 0.2143304 6 -0.93314 0.3868
daytwo -0.100 0.2109008 6 -0.47416 0.6522
lightL2:daytwo -1.525 0.2982588 6 -5.11301 0.0022
Correlation:
(Intr) lghtL2 daytwo
lightL2 -0.707
daytwo -0.696 0.492
lightL2:daytwo 0.492 -0.696 -0.707
Standardized Within-Group Residuals:
Min Q1 Med Q3
Max
-0.36863373 -0.15741132 0.03092751 0.14569214 0.32591770
Number of Observations: 16
Number of Groups:
subject day %in% subject
8 16
My FIRST problem is that I'm not quite sure how to analyse the above output.
My SECOND problem is when I try to use glht(), to get multiple comparisons:
summary(glht(m1,linfct=mcp(day="Tukey")))
I get an error message:
Error in as.vector(x, mode) : invalid 'mode' argument
I"m not sure where this comes from. I've tried everything I (and my
labmates, we are a bunch of field biologists, not statisticians) can think
of, but this keeps coming back. Is it because glht() isn't appropriate for
2-way ANOVAs? If that's the problem, what is the correct way to do this?
Or am I going about this completely wrong from the get-go?
Thanks for all the help you can provide!
K
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