I have been trying to reproduce an analysis from Douglas Montgomery�s book on design and analysis of experiments. Table 6.10 of example 6.2 on page 246, gives a table as follows:
> NPK <- expand.grid(A=mp,B=mp,C=mp,D=mp) > Rate <- c(45,71,48,65,68,60,80,65,43,100,45,104,75,86,70,96) > filtration <- cbind(NPK,Rate) > filtration A B C D Rate 1 - - - - 45 2 + - - - 71 3 - + - - 48 4 + + - - 65 5 - - + - 68 6 + - + - 60 7 - + + - 80 8 + + + - 65 9 - - - + 43 10 + - - + 100 11 - + - + 45 12 + + - + 104 13 - - + + 75 14 + - + + 86 15 - + + + 70 16 + + + + 96
Two additional tables follow. Table 6-11 for contracts constants and Table 6-12 for Factor effects estimates.
So far my attempts at fitting the model gives me very different effect estimates. This I guess is because I have not set the right contrasts?
Can anyone explain to me how I could set the correct contrasts in R to estimate the effects in this unreplicated 2^4 factorial?
Thanks in advance,
Peter
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