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...lculated as 0.4 correctly, but the p-value is stated by R as 1, though in fact it should be 20/21=0.9524 As I say this is just one example of quite a lot of errors of this kind that I am finding. If you want more examples I can try to be more systematic about tracking them down. Thank you, David Allwright. ----------------------------------------------------------------------------- Dr DJ Allwright E-mail : allwrigh at maths.ox.ac.uk OCIAM(Oxford Centre for Industrial and Applied Mathematics) Mathematical Institute Telephone : [+44](0)1865-280604 24-29 St.Giles'...

I've fixed this by adding 0.5/mn to q. The problem (at least in principle) with multiplying them all up is integer overflow. By the time 0.5/mn underflows to zero, missing one value in the distribution won't matter. -thomas On Fri, 18 Dec 2009, David John Allwright wrote: > Dear Thomas, Right, thank you. Yes, I haven't looked at the source code > (because I don't know C) but something like what you mention could well cause > the kind of problems I am seeing: a loop being exectued one too few or one > too many times. And yes, I think t...

...s. And yes, I think those quantities should be multiplied up by m*n to all become integers so we escape rounding error problems. David. ------------------------------------------------------------------------------ On Wed, 16 Dec 2009, tlumley at u.washington.edu wrote: > On Tue, 15 Dec 2009, allwrigh at maths.ox.ac.uk wrote; (in part) > >> >> x<-1:5 >> y<-c(2.5,4.5) >> ks.test(x,y) >> >> The value of the D_2,5 statistic is calculated as 0.4 correctly, but the >> p-value is stated by R as 1, though in fact it should be 20/21=0.9524 > > &...

...his by adding 0.5/mn to q. The problem (at least in principle) > with multiplying them all up is integer overflow. > > By the time 0.5/mn underflows to zero, missing one value in the distribution > won't matter. > > -thomas > > > On Fri, 18 Dec 2009, David John Allwright wrote: > >> Dear Thomas, Right, thank you. Yes, I haven't looked at the source code >> (because I don't know C) but something like what you mention could well >> cause the kind of problems I am seeing: a loop being exectued one too few >> or one too many times...