IAPlot {FrF2}R Documentation

Main Effects and Interaction Plots

Description

Main effects plots and interaction plots are produced. The other documented functions are not intended for users.

Usage

MEPlot(obj, main = paste("Main effects plot for", respnam), 
    pch = 15, cex.xax = par("cex.axis"), cex.yax = cex.xax, mgp.ylab = 4, 
    cex.title = 1.5, cex.main = par("cex.main"), 
    lwd = par("lwd"), abbrev = 3)

IAPlot(obj, main = paste("Interaction plot matrix for", respnam), 
    pch = c(15, 17), cex.lab = par("cex.lab"), cex = par("cex"), 
    cex.xax = par("cex.axis"), cex.yax = cex.xax, cex.title = 1.5, 
    lwd = par("lwd"), abbrev = 4, show.alias = FALSE)
         
intfind(i, j, mat)

check(obj)

remodel(obj)

Arguments

obj a linear model object with 2-level factors or numerical 2-level variables (CAUTION: numerical x-variable have to be coded as -1 and +1 only!); the structure must be such that effects are either fully aliased or orthogonal, like in a fractional factorial 2-level design
main overall title for the plot assembly
pch Plot symbol number MEPlot, or vector of two plot symbol numbers for the lower and higher level of the trace factor iap
cex.xax size of x-axis annotation, defaults to cex.axis-parameter
cex.yax size of y-axis annotation, defaults to cex.xax
mgp.ylab horizontal placement of label of vertical axis in MEPlot
cex.title multiplier for size of overall title (cex.main is multiplied with this factor)
cex.main size of individual plot titles in MEPlot
cex.lab Size of variable names in diagonal panels of interaction plots produced by IAPlot.
cex size of plot symbols in interaction plots
lwd line width for plot lines and axes
abbrev number of characters shown for factor levels
show.alias if TRUE, the interaction plot shows the number of the list entry from aliases(obj)$aliases (cf. aliases) in order to support immediate diagnosis of which depicted interaction may be due to other than the shown effect because of aliasing
i integer, for internal use only
j integer, for internal use only
mat matrix, for internal use only

Details

MEPlot produces plots of all main effects in the model, IAPlot produces plots of all interaction effects in the model, intfind is an internal function not directly useful for users. check is an internal function for checking whether the model complies with assumptions (fractional factorial of 2-level factors with full or no aliasing, not partial aliasing), remodel is an internal function that redoes the model into -1 and 1 coding, regardless of the contrasts that have been used for the factors (note that numerical data are not changed, i.e. they have to be in -1 and 1 coding in order for the package to work).

Value

MEPlot and IAPlot are used for their side effects only.
The internal function check is used within other functions for checking whether the model is a fractional factorial with 2-level factors and no partial aliasing, as requested for the package to work. It is applied to remodeled objects only and returns a logical. If the returned value is FALSE, the calling function fails.
The internal function intfind returns an integer (length 1 or 0). It is not useful for users.
The internal function remodel is applied to a linear model object and returns a list of two components:

model is the redone model with x-variables recoded to numeric -1 and 1 notation and aov objects made into “pure” lm objects
labs is a list preserving the level information from original factors (levels are minus and plus for numerical variables)

Author(s)

Ulrike Groemping

References

Box G. E. P, Hunter, W. C. and Hunter, J. S. (2005) Statistics for Experimenters, 2nd edition. New York: Wiley.

See Also

FrF2-package for examples


[Package FrF2 version 0.9-1 Index]