[R] qqnorm in R-0.63.3

Peter Dalgaard BSA p.dalgaard at biostat.ku.dk
Tue Mar 16 14:12:56 CET 1999

Tino Reinhardt <h0444idm at student.hu-berlin.de> writes:

> try	x <- table(rnorm(1000)	# or similar and
> 	qqnorm(x,type="s")	# in 0.63.2 and 63.3

You mean
x <- rnorm(1000)

> Well, the NEWS-file says `qqnorm() uses ppoints() and returns a list
> with x sorted along y.´ and, IMHO, that explains the slopes.
> But is it generally a bad idea to connect the observed points and
> print a nice line instead?
> and if not, could anyone explain why it should be x sorted along y?

I believe the reason given at the time was Splus compatibility. We're
still not compatible when it comes to NA handling, though. S(-plus
3.4) gives NA where the original arguments has NA, R just omits NA
cases. This is a bit silly, because the major use I can think of for
the current convention is to obtain a parallel vector to x with the
"expected normal scores" (or an approximation thereof).

To get a prettier plot, use qqnorm(sort(x),type="s")

Come to thik of it wouldn't it be nice to have a general sort=
plotting parameter?

   O__  ---- Peter Dalgaard             Blegdamsvej 3  
  c/ /'_ --- Dept. of Biostatistics     2200 Cph. N   
 (*) \(*) -- University of Copenhagen   Denmark      Ph: (+45) 35327918
~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk)             FAX: (+45) 35327907
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