Based on integration it appears that .0721 is correct. > integrate(function(x) exp(-x^2/2)/(2*pi)^.5, -Inf, -1.46) 0.07214504 with absolute error < 1.2e-07
On 11/25/06, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote: > 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 > place? > cheers, > > Rolf Turner > [EMAIL PROTECTED] > > ______________________________________________ > R-help@stat.math.ethz.ch mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. > ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
