[R] paste ?

[Bill Venables]

> As Peter helpfully pointed out mn was a vector, so here is the corrected 
> version:
>   bland <- function (x) #accepts two columns
> {
> mn <<- 0.5*(x[,1]+x[,2]
> diff <- x[,1]-x[,2]
> plot(mn,diff,pch=16,xlab="Mean",ylab="Difference",
> main = "Bland Altman plot",
> sub= paste("Mean = ",formatC(mean(diff),digits=3)))
> abline(h=mean(diff),lty=2)
> abline(h=mean(diff)+c(2,-2)*sqrt(var(diff)))
> }

Two small points.  The line

mn <<- 0.5*(x[,1]+x[,2])

is either a mistake, or it makes this a dangerous function for
public distribution.  ("Superassignment? Just say 'No'")

Secondly, I'm curious about the history of this kind of plot.
I've only heard it called a "Tukey mean difference" plot, (and
Trellis graphics has a function, tmd(), that does it, but no one
knows about it...).  Does anyone know who invented it?

Bill Venables.

-- 
Bill Venables,      Statistician,     CMIS Environmetrics Project
CSIRO Marine Labs, PO Box 120, Cleveland, Qld,  AUSTRALIA.   4163
Tel: +61 7 3826 7251           Email: Bill.Venables at cmis.csiro.au

Fax: +61 7 3826 7304      http://www.cmis.csiro.au/bill.venables/



-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-
r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html
Send "info", "help", or "[un]subscribe"
(in the "body", not the subject !)  To: r-help-request at stat.math.ethz.ch
_._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._