Adaikalavan Ramasamy
2004-Nov-04 12:27 UTC
[R] (no subject)-about the waring/errors in ks.test
[In future, please press reply all as there might be others in the mailing list who can help you] Without a (short) reproducible example, it would be difficult to say. BTW, I think you have mistyped the error/warning message. Does it actually say "cannot compute _correct_ p-value" or "cannot compute _exact_ p-value". See example below.> wilcox.test( 1:3, 1:10 )Wilcoxon rank sum test with continuity correction data: 1:3 and 1:10 W = 4.5, p-value = 0.08964 alternative hypothesis: true mu is not equal to 0 Warning message: Cannot compute exact p-value with ties in: wilcox.test.default(1:3, 1:10) On Thu, 2004-11-04 at 00:31, fang lai wrote:> Dear Adaikalavan, > Many thanks for your suggestions. The message > "cannot compute correct p-values with ties in" > sometimes shows up as an error (in most cases I have > small group for the test), and sometimes shows up as > waring when I typed warning() (in most cases the group > I am testing is relatively large). But all the data > are from the same data set. > So what is the distinction between these two? > Many thanks, > > Fang > > > --- Adaikalavan Ramasamy <ramasamy at cancer.org.uk> > wrote: > > > Reading the posting guide will tell you (among other > > things) to : > > a) use a sensible subject line > > b) give a reproducible example when possible > > > > See other comments below. > > > > On Wed, 2004-11-03 at 19:04, fang lai wrote: > > > Hi there, > > > When I ran the wilcox.exact test, it always shows > > > "number of items to replace is not a multiple of > > > replacement length" > > > However, according to the help it seems to be > > able to > > > handle sample of different size. > > > > I think the error refers to incorrect lengths during > > assignment. See > > example below. > > > > > aaa <- matrix( 1:4, nr=2 ) > > > aaa > > [,1] [,2] > > [1,] 1 3 > > [2,] 2 4 > > > aaa[1, ] > > [1] 1 3 > > > > > aaa[1, ] <- 1:3 > > Error in "[<-"(`*tmp*`, 1, , value = 1:3) : > > number of items to replace is not a multiple of > > replacement length > > > > Or you might be trying something like > > > > > aaa <- matrix( 1:4, nr=2 ) > > > aaa[1, ] <- wilcox.test( 1:3, 1:10 ) > > Error in "[<-"(`*tmp*`, 1, , value > > wilcox.test(1:3, 1:10)) : > > number of items to replace is not a multiple of > > replacement length > > > > > > Wilcoxon and all other two-group test statistics > > (when pairing is not > > involved) can handle groups of different size. > > Try wilcox.test( 1:3, 1:10 ). > > To extract p-value only, do wilcox.test( 1:3, 1:10 > > )$p.value > > > > > What does this message indicate, and will it cause > > a > > > problem of the resulting p-value? > > > > Not directly. You could be expecting p-values to be > > in, say the 5th > > column, but it might be stored elsewhere. But in > > your case I think the > > results will not be stored anyway. > > > > > Also, when I run the ks.test(), it shows > > sometimes > > > that > > > cannot compute correct p-values with ties in: > > > ks.test(income.perm[(data[, 3] == 59) & (data[, 2] > > => > > 1)], income.perm[(data[, ... > > > > Is this a warning or an error ? There is a > > distinction. > > > > > And sometime it shows results and sometimes it > > just > > > return NULL. When it shows the results, does it > > mean > > > that it had some kind of continuity correction or > > > other adjustment so that I could believe the > > results? > > > Many thanks, > > > > > > Fang > > > > > > > > > ====> > > Lai, Fang > > > > > > PhD candidate > > > University of California, Berkeley > > > Department of Agricultural and Resource Economics > > > 314 Giannini Hall, Berkeley, CA 94720-3310 > > > tel: (510) 643 - 5421(O) > > > (510) 847 - 9811(Cell) > > > fax: (510) 643 - 8911 > > > email: lai at are.berkeley.edu > > > http://www.are.berkeley.edu/jobmarket/fang.html > > > > > > ______________________________________________ > > > R-help at 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 > > > > > > > > > > ====> Lai, Fang > > PhD candidate > University of California, Berkeley > Department of Agricultural and Resource Economics > 314 Giannini Hall, Berkeley, CA 94720-3310 > tel: (510) 643 - 5421(O) > (510) 847 - 9811(Cell) > fax: (510) 643 - 8911 > email: lai at are.berkeley.edu > http://www.are.berkeley.edu/jobmarket/fang.html > > __________________________________________________