Dear R users,



I have used the AlgDesign package to construct a D-optimal exp. design from
a file containing a set of allowed runs. The code for the optFederov call is
below:



#Using optFederov ------------------------------

library(AlgDesign)

options(contrasts=c("contr.sum","contr.poly"))

file<- read.table("C:/Upstream/Designs/Vodacom Tanzania phase1
grammar/JMP_allowed.txt",sep="\t",header=TRUE,strip.white=TRUE)

formula<-as.formula("~structure+intro + intro/intro1 + concept +
concept/concept1 + prize")

design<-optFederov(formula, data=file, nTrials=48, evaluateI=T,
criterion="D", maxIteration=10000, nRepeats=300,

  approximate=F,args=T)

#------------------------------------------------------------------------------------------------------------------------------------------------------------------------



I also use the Rcmdr interface at time for ease, when using the Rcmdr
interface is used the same data file, formula and desired number of runs. I
also set the seed to that of the optFederov call above. I was expected the
same design to be generated. However, when I examine the balance of the
generated design, Dopt.design and optFederov yield different designs. Given
that Dopt.design is a DoE wrapper for optFerderov I am confused as to why
this is happening.



#Using R-commander

Dataset.Dopt <- Dopt.design(48, data= file, formula,

   nRepeat= 300 ,randomize= TRUE, seed=403)



Apologies if this has a simple answer, I have consulted the R-help archives,
but have not found an answer as yet. If the forum could offer reasons as to
why this is happening I would be most grateful.



Regards



M. Griffiths

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