On Tue, 15 Dec 2009, allwr...@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
What we seem to have here is a rounding error problem. In ks.c:psmirnov2x, there is a double loop including if(fabs(i / md - j / nd) > q) u[j] = 0; where md=2, nd=5, and q=3/10. Now, to full precision abs(1/2 - 4/5) > 3/10 is false, but at least on my MacBook it is true in C double precision. I'm not sure why the loop is working with doubles, since multiplying by m*n should make everything an integer. -thomas Thomas Lumley Assoc. Professor, Biostatistics tlum...@u.washington.edu University of Washington, Seattle ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel