Dear R-list members,

I compared my statistics with my supervisor yesterday. He is using STATISTICA, 
I am using R. We both loaded the same data-file and did a two-way ANOVA with 
treatment and trial as factors; treatment means were then compared to the 
untreated control using Dunnett's test. Surprisingly, we got different values, 
especially the F values differed. In the following Dunnett's test, some 
treatments were significant in R, but not in STATISTICA. We checked the basic 
settings of the programs and found out, that STATISTICA is using 
"sigma-restricted parametrization" and "type VI sum of squares" for the 
calculations, but so far, I could not find any information about the sum of 
squares type, which is applied in R. Is it possible, that these settings are 
the reason for the different values we got? And how can I change in R these 
settings?

Here the code I used:
bt_assay_devtime_Model <- aov(developmenttime~treatment+run+treatment*run, 
data=bt_assay)
summary(bt_assay_devtime_Model)
postHocs_bt_assay_devtime <- glht(bt_assay_devtime_Model, 
linfct=mcp(treatment="Dunnett"), base=1)
summary(postHocs_bt_assay_devtime)
confint(postHocs_bt_assay_devtime)

Thanks a lot for your help!
Simone

Eisenring Michael, Msc.
PhD Student

Federal Department of Economic Affairs, Education and Research
EAER
Institute of Sustainability Sciences ISS
Biosafety

Reckenholzstrasse 191, CH-8046 Z�rich
Tel. +41 44 37 77181
Fax +41 44 37 77201
michael.eisenr...@agroscope.admin.ch<mailto:michael.eisenr...@agroscope.admin.ch>
www.agroscope.ch<http://www.agroscope.ch/>


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