aliases {FrF2} | R Documentation |
Function to provide a human-friendly format for the alias structure of a fractional factorial 2-level design
aliases(fit, code = FALSE)
fit |
a linear model object with only 2-level factors as x-variables; the function will return an error, if the model contains partially aliased effects (like interactions in a Plackett-Burman design for most cases) |
code |
if TRUE, requests that aliasing is given in code letters (A, B, C etc.) instead of (potentially lengthy) variable names; in this case, a legend is included in the output object. |
A list with two elements:
legend |
links the codes to variable names, if code=TRUE . |
aliases |
is a list of vectors of aliased effects. |
Ulrike Groemping
Box G. E. P, Hunter, W. C. and Hunter, J. S. (2005) Statistics for Experimenters, 2nd edition. New York: Wiley.
FrF2-package
for information on the package,
alias
for the built-in R-function,
IAPlot
for effects plots
### Injection Molding Experiment. Box et al. 1978. data(BM93.e3.data) #from BsMD iMdat <- BM93.e3.data[1:16,2:10] #only original experiment # make data more user-friendly colnames(iMdat) <- c("MoldTemp","Moisture","HoldPress","CavityThick", "BoostPress","CycleTime","GateSize","ScrewSpeed","y") # determine aliases with all 2-factor-interactions aliases(lm(y ~ (.)^2, data = iMdat)) # coded version aliases(lm(y ~ (.)^2, data = iMdat), code=TRUE) # determine aliases with all 3-factor-interactions aliases(lm(y ~ (.)^3, data = iMdat), code=TRUE) # determine aliases for unaliased model aliases(lm(y ~ ., data = iMdat))