[R] Aov: SE's for split plot
Prew, Paul
Paul.Prew at ecolab.com
Fri Nov 13 22:37:29 CET 2009
Hello,
Can anyone explain why the following message appears for the function model.tables, where se=T? In the V&R MASS text, p.285 the se=T option works for a split plot example that seems similar to my operation. But the model.tables documentation, in the Arguments section for "se", states "should standard errors be computed?".
"Warning: Warning in model.tables.aovlist(Magic.aov, type = "means", se=T):
SE's for type 'means' are not implemented yet"
I am trying to get the Standard Errors (SE's) for a split plot using the aov function. I'm not sure, it may be a split-split plot design. There are two crossed factors: 1)Formula 2)SwatchType.
* Formula is applied to the whole plots. WP = Load.
* Each Whole plot is further divided into 3 split plots. SP = BackrNbr, 3 BackrNbrs within a single Load.
* Each split plot is the block for a completely randomized design using factor = SwatchType. All 6 SwatchTypes are applied within each BackrNbr
Magic.aov<-aov(SoilRemoval~Formula*SwatchType+Error(Load/BackrNbr),data=Magic.dat)
model.tables(Magic.aov, type="means",se=T) ### the table of means are printed, no SE's
> str(Magic.dat)
'data.frame': 162 obs. of 7 variables:
$ BackrNbr : Factor w/ 27 levels "1","2","3","4",..: 1 1 1 1 1 1 2 2 2 2 ...
$ Load : Factor w/ 9 levels "1","2","3","4",..: 1 1 1 1 1 1 1 1 1 1 ...
$ Formula : Factor w/ 3 levels "CONTROL","EXP1",..: 2 2 2 2 2 2 2 2 2 2 ...
$ SwatchType : Factor w/ 6 levels "DMO","Dust.Seb",..: 2 6 1 5 4 3 2 6 1 5 ...
$ L.Initial : num 71.2 73.9 69.3 58.6 40.6 ...
$ L.Final : num 89.8 75.6 70.5 69.6 58.9 ...
$ SoilRemoval: num 75.08 7.88 4.71 29.44 33.15 ...
Thank you for your consideration,
Paul
Paul Prew | Statistician
651-795-5942 | fax 651-204-7504
Ecolab Research Center | Mail Stop ESC-F4412-A
655 Lone Oak Drive | Eagan, MN 55121-1560
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