**Anorexia**. The file

http://www.utdallas.edu/~ammann/stat3355scripts/anorexia.txt

contains pre-treatment and post-treatment weights of anorexia patients. These patients were randomly
assigned to one of three treatments, *Cont, CBT, FT*. We would like to show a comparison of
pre-treatment weights. We also would like to show how patient weight gains compared across these
treatments with weight gain expressed as a percentage increase from pre-treatment.

Anorexia = read.table("http://www.utdallas.edu/~ammann/stat3355scripts/anorexia.txt", header=TRUE, row.names=1) Trtcol = c("blue","IndianRed","green") plot(Prewt ~ Treat, data=Anorexia,xlab="Treatment",ylab="Weight",col=Trtcol) n = dim(Anorexia)[1] title(paste("Pre-treatment Weight of",n,"Anorexia Patients")) Wtgain = Anorexia[,"Postwt"]-Anorexia[,"Prewt"] Wtgainpc = 100*Wtgain/Anorexia[,"Prewt"] plot(Wtgainpc ~ Treat, data=Anorexia,xlab="Treatment",ylab="Weight gain %",col=Trtcol) title(paste("Relative Weight Gain of",n,"Anorexia Patients")) #note that CBT has 6 observations that are unusually high.

Consider all patients who lost weight during the study. Determine the number of such patients in each treatment group.

table(Anorexia[,"Treat"],Wtgain < 0)

Next consider those patients in the upper 25% of percentage weight gain. Determine the number of such patients in each treatment group.

uq = quantile(Wtgainpc,.75) table(Anorexia[,"Treat"],Wtgain >= uq)

2014-12-08