boxplotTTlist function

Parallel Boxplots After Tail Transformation For a List

For a list of vectors of pair differences, plots boxplots for differences after applying the same tail transformation to all differences. See the help file for ttrans() for information about the transformation.

boxplotTTlist(ylist, p=-1, qu=.95, tcks=NULL, ylab="", xlab="", main="",
         cex.lab=.8, cex.main=.8, cex.axis=.8, symZero=TRUE)

Arguments

• ylist: A list of vectors of pair differences. An error will result if ylist is not a list. The vectors need not have the same lengths, and this makes boxplotTTlist() more flexible than boxplotTT().
• p: The power of the transformation. See the help file for the ttrans() function.
• qu: One number strictly between 0 and 1, commonly 0.9 or 0.95. Define beta to be the qu quantile of abs(as.vector(y)). Then, values between -beta and beta are not transformed.
• tcks: A vector of untransformed values to become tick marks for the y axis after transformation. Although the y axis was transformed, it is labeled with corresponding untransformed values given by tcks. If is.null(tcks), then the y axis has no tick marks.
• ylab: Label for the y-axis.
• xlab: Label for the x-axis.
• main: Title for the plot. If main="", then no title appears, and the sample size appears above each boxplot. If you prefer no title and no sample sizes, set main=" ".
• cex.lab: Sets the label size for the boxplot using the standard graphics parameter cex.lab.
• cex.main: Sets the title size for the boxplot using the standard graphics parameter cex.main.
• cex.axis: Sets the axis size for the boxplot using the standard graphics parameter cex.axis.
• symZero: If TRUE, makes the y-axis symmetric about zero. If FALSE, the maximum and minimum values in ylist determine the y-axis.

Details

See the help file for ttrans() for an explanation of the transformation.

Returns

Parallel boxplots after tail transformation.

References

Rosenbaum, P. R. (2022) doi:10.1080/00031305.2022.2063944 A new transformation of treated-control matched-pair differences for graphical display. American Statistician, 76, 346-352.

Ye, T., Small, D. S. and Rosenbaum, P. R. (2022) doi:10.1214/22-AOAS1611 Dimensions, power and factors in an observational study of behavioral problems after physical abuse of children. Annals of Applied Statistics, 16, 2732-2754.

Author(s)

Paul R. Rosenbaum

See Also

ttrans

Examples

# Makes Figure 5(ii) in Rosenbaum (2022).
# See also Figure 1 in Ye et al. (2022).

data(aHDL)
y<-t(matrix(aHDL$hdl,4,406))
y<-y[,c(1,3,2,4)]
colnames(y)<-c("D","N","R","B")

TC<-c(y[,1]-y[,2],y[,1]-y[,3],y[,1]-y[,4])
CC<-c(y[,2]-y[,3],y[,2]-y[,4],y[,3]-y[,4])
CC<-c(CC,-CC)

ylist<-list(TC=TC,CC=CC)

boxplotTTlist(ylist,tcks=c(-80,-40,-20,0,20,40,80),ylab="HDL Difference")