[R] OT: P(Z <= -1.46).

rolf at math.unb.ca rolf at math.unb.ca
Sat Nov 25 16:21:13 CET 2006

In checking over the solutions to some homework that I had assigned I
observed the fact that in R (version 2.4.0) pnorm(-1.46) gives
0.07214504.  The tables in the text book that I am using for the
course give the probability as 0.0722.

Fascinated, I scanned through 5 or 6 other text books (amongst the
dozens of freebies from publishers that lurk on my shelf) and found
that some agree with R (giving P(Z <= -1.46) = 0.0721) and some agree
with the first text book, giving 0.0722.

It is clearly of little-to-no practical import, but I'm curious as to
how such a discrepancy would arise in this era.  Has anyone any
idea?  Is there any possibility that the algorithm(s) used to
calculate this probability is/are not accurate to 4 decimal places?

Could two algorithms ``reasonably'' disagree in the 4th decimal

					Rolf Turner
					rolf at math.unb.ca

More information about the R-help mailing list