FrF2-package {FrF2} | R Documentation |
This package creates regular and non-regular Fractional Factorial designs. Furthermore, analysis tools for Fractional Factorial designs with 2-level factors are offered (main effects and interaction plots for all factors simultaneously, cube plot for looking at the simultaneous effects of three factors, full or half normal plot, alias structure in a more readable format than with the built-in function alias).
The package works together with packages DoE.base and DoE.wrapper.
The package is currently subject to intensive development; most key functionality is now included. Some changes to input and output structures may still occur. Please contact me, if you have suggestions.
This package designs and analyses Fractional Factorial experiments with 2-level factors.
Regular (function FrF2
) and non-regular (function pb
) 2-level fractional factorial
designs can be generated.
Regular fractional factorials can be generated as blocked or split-plot designs, and hard-to-change
factors can be specified in order to keep the number of level changes low.
Analysis facilities work for completely aliased designs only,
i.e. e.g. not for analysing Plackett-Burman designs with interactions.
Functions fac.design
, fractionate
or oa.design
from
Chambers and Hastie (1993) have been used as role models e.g. for
the option factor.names
or for outputting a data frame with attributes.
However, S compatibility has not been considered in devising this package.
In terms of analysis, the package works on linear models and enables convenient main effects and
interaction plots (functions MEPlot
and IAPlot
) similar to those
offered by Minitab software for all factors simultaneously, even though especially the
interactions are often aliased, i.e. the model is typically singular.
For the (rare) case of suspected three-factor-interactions, function
cubePlot
displays a cube with corners labeled with the (modeled)
means of three factors simultaneously.
Furthermore, the function DanielPlot
from package BsMD has been
modified to automatically label effects significant according to the
Lenth-criterion, and to provide more usage comfort to the analyst.
Finally, the function aliases
determines the alias structure of a
Fractional Factorial 2-level design in a format more suitable for human readers
than the output from the built-in function alias
.
CAUTION: Note that the analysis facilities currently do not make use of the design information attached to the design. For example, an effects plot function will treat a linear model based on a split-plot-design in the same way as if the design were a standard fractional factorial.
Ulrike Groemping
Maintainer: Ulrike Groemping <groemping@bht-berlin.de>
Box G. E. P, Hunter, W. C. and Hunter, J. S. (2005) Statistics for Experimenters, 2nd edition. New York: Wiley.
Chambers, J.M. and Hastie, T.J. (1993). Statistical Models in S, Chapman and Hall, London.
Chen, J., Sun, D.X. and Wu, C.F.J. (1993) A catalogue of 2-level and 3-level orthogonal arrays. International Statistical Review 61, 131-145.
Daniel, C. (1959) Use of Half Normal Plots in Interpreting Two Level Experiments. Technometrics, 1, 311-340.
Hedayat, A.S., Sloane, N.J.A. and Stufken, J. (1999) Orthogonal Arrays: Theory and Applications, Springer, New York.
Lenth, R.V. (1989) Quick and easy analysis of unreplicated factorials. Technometrics, 31, 469-473.
Mee, R. (2009). A Comprehensive Guide to Factorial Two-Level Experimentation. New York: Springer.
Montgomery, D.C. (2001). Design and Analysis of Experiments (5th ed.). Wiley, New York.
Plackett, R.L.; Burman, J.P. (1946) The design of optimum multifactorial experiments. Biometrika 33, 305-325.
The key design generating functions: FrF2
, pb
S3 class design
Related packages:
DoE.base
,
DoE.wrapper
,
BsMD
;
Graphical analysis functions: MEPlot
, IAPlot
, cubePlot
,
DanielPlot
Analysis of alias structure for linear models of FrF2
designs: aliases
### for examples on design generation, cf. functions pb and FrF2 ### 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") # linear model with all main effects and 2-factor interactions iM.lm <- lm(y ~ (.)^2, data = iMdat) # determine aliases aliases(iM.lm) # coded version aliases(iM.lm, code=TRUE) # normal plot of effects, default is autolabel with alpha=0.05 DanielPlot(iM.lm) DanielPlot(iM.lm,code=TRUE) DanielPlot(iM.lm,code=TRUE,alpha=0.5) # half normal plot of effects DanielPlot(iM.lm,code=TRUE,alpha=0.5,half=TRUE) # main effects plots MEPlot(iM.lm) # interaction plots IAPlot(iM.lm) # interaction plots with attention drawn to aliases IAPlot(iM.lm, show.alias=TRUE) # alias groups corresponding to interaction plots aliases(iM.lm)$aliases[9:15] # cube plot of three factors # (not very useful for this model, for demonstration only) ## per default, modeled means are shown ## this does not make a difference here, since the main effect of ## ScrewSpeed is confounded with the MoldTemp:HoldPress:BoostPress ## interaction, so that the three-factor-interaction is indirectly included ## in the modeled means cubePlot(iM.lm, "MoldTemp", "HoldPress", "BoostPress") ## modeled means without a three-factor interaction cubePlot(lm(y ~ (MoldTemp+HoldPress+BoostPress)^2, data = iMdat), "MoldTemp", "HoldPress", "BoostPress") ## modeled=FALSE reverts to showing the apparent three-factor interaction cubePlot(lm(y ~ (MoldTemp+HoldPress+BoostPress)^2, data = iMdat), "MoldTemp", "HoldPress", "BoostPress", modeled=FALSE) ## cubePlot also works on raw data cubePlot(iMdat$y, iMdat$MoldTemp, iMdat$HoldPress, iMdat$BoostPress) ## plotting functions also work directly on designs, ## if these have been generated from functions FrF2 or pb: plan <- FrF2(16, 7) plan <- add.response(plan, rnorm(16)) MEPlot(plan) IAPlot(plan) DanielPlot(plan)