On Thu, 2 Jun 2005, Liaw, Andy wrote: > By post hoc I guess you meant pairwise comparisons. You might want to check > out the npmc package on CRAN. >
?oneway_test in `coin' has an example, essentially ### Length of YOY Gizzard Shad from Kokosing Lake, Ohio, ### sampled in Summer 1984, Hollander & Wolfe (1999), Table 6.3, page 200 YOY <- data.frame(length = c(46, 28, 46, 37, 32, 41, 42, 45, 38, 44, 42, 60, 32, 42, 45, 58, 27, 51, 42, 52, 38, 33, 26, 25, 28, 28, 26, 27, 27, 27, 31, 30, 27, 29, 30, 25, 25, 24, 27, 30), site = factor(c(rep("I", 10), rep("II", 10), rep("III", 10), rep("IV", 10)))) ### Kruskal-Wallis test, approximate exact p-value kw <- kruskal_test(length ~ site, data = YOY, distribution = approximate(B = 9999)) kw pvalue(kw) ### Nemenyi-Damico-Wolfe-Dunn test (joint ranking) ### Hollander & Wolfe (1999), page 244 ### (where Steel-Dwass results are given) if (require(multcomp)) { NDWD <- oneway_test(length ~ site, data = YOY, ytrafo = function(data) trafo(data, numeric_trafo = rank), xtrafo = function(data) trafo(data, factor_trafo = function(x) model.matrix(~x - 1) %*% t(contrMat(table(x), "Tukey"))), teststat = "maxtype", distribution = approximate(B = 90000)) ### global p-value print(pvalue(NDWD)) ### sites (I = II) != (III = IV) at alpha = 0.01 (page 244) print(pvalue(NDWD, adjusted = TRUE)) } the key step is xtrafo = function(data) trafo(data, factor_trafo = function(x) model.matrix(~x - 1) %*% t(contrMat(table(x), "Tukey"))) where you may specify _any_ contrast matrix, for example just a subset of all pairwise comparisons you are willing to pay for. Torsten > Andy > > > From: [EMAIL PROTECTED] > > > > I´m looking for a program with a post hoc kruskall Wallis > > test like the Tukey- > > type non parametric test of ZAR(Biostatistical Analysis > > 2ºEdition). SSPS > > hasn´t got any non parametric post host test. I don´t know if > > R has an > > appropiate post hoc non parametric test. I´m not sure if NDWD > > test of the > > package "coin" is an appropiate test or if the package "npmc" > > is a best option. > > Thank you > > > > > > Alfredo Bermúdez > > > > > > > > > > > > > > > > ------------------------------------------------- > > > > > > ----- Fin del mensaje reenviado ----- > > > > ______________________________________________ > > 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 > > > > > > > > ______________________________________________ > 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 > > ______________________________________________ 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