R version 3.0.2 (2013-09-25) -- "Frisbee Sailing"
Copyright (C) 2013 The R Foundation for Statistical Computing
Platform: i686-pc-linux-gnu (32-bit)

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> x <- c(20,28,24,27,23,28,27,19,28,11,25,20,20,24,25,28,24,21,22,20,20,23,21,12,23,28,24,24,25,21,26,28,21,27,22,23,24,22,23,25,21,22,20,21,19,26,20,22,23,22,24,23,23,27,21,23,25,23,22,28,28,20,18)
> gp <- function(lambda, p)
+ {
+ (p^lambda-(1-p)^lambda)/lambda
+ }
> sortx <- sort(x)
> c <- array(NA,dim=c(201))
> for (i in 1:201)
+ {
+ if (i != 101) c[i] <- cor(gp(ppoints(x), lambda=(i-101)/100),sortx)
+ }
> postscript(file="/var/wessaorg/rcomp/tmp/164r81382549271.ps",horizontal=F,onefile=F,pagecentre=F,paper="special",width=8.3333333333333,height=5.5555555555556) 
> plot((-100:100)/100,c[1:201],xlab='lambda',ylab='correlation',main='PPCC Plot - Tukey lambda')
> grid()
> dev.off()
null device 
          1 
> 
> #Note: the /var/wessaorg/rcomp/createtable file can be downloaded at http://www.wessa.net/cretab
> load(file="/var/wessaorg/rcomp/createtable")
> 
> a<-table.start()
> a<-table.row.start(a)
> a<-table.element(a,'Tukey Lambda - Key Values',2,TRUE)
> a<-table.row.end(a)
> a<-table.row.start(a)
> a<-table.element(a,'Distribution (lambda)',1,TRUE)
> a<-table.element(a,'Correlation',1,TRUE)
> a<-table.row.end(a)
> a<-table.row.start(a)
> a<-table.element(a,'Approx. Cauchy (lambda=-1)',header=TRUE)
> a<-table.element(a,c[1])
> a<-table.row.end(a)
> a<-table.row.start(a)
> a<-table.element(a,'Exact Logistic (lambda=0)',header=TRUE)
> a<-table.element(a,(c[100]+c[102])/2)
> a<-table.row.end(a)
> a<-table.row.start(a)
> a<-table.element(a,'Approx. Normal (lambda=0.14)',header=TRUE)
> a<-table.element(a,c[115])
> a<-table.row.end(a)
> a<-table.row.start(a)
> a<-table.element(a,'U-shaped (lambda=0.5)',header=TRUE)
> a<-table.element(a,c[151])
> a<-table.row.end(a)
> a<-table.row.start(a)
> a<-table.element(a,'Exactly Uniform (lambda=1)',header=TRUE)
> a<-table.element(a,c[201])
> a<-table.row.end(a)
> a<-table.end(a)
> table.save(a,file="/var/wessaorg/rcomp/tmp/2s9ps1382549271.tab") 
> 
> try(system("convert tmp/164r81382549271.ps tmp/164r81382549271.png",intern=TRUE))
character(0)
> 
> 
> proc.time()
   user  system elapsed 
  1.184   0.251   1.404