Thank you! It's what I want :) But I can't make it work. I'm working with R version 2.7.1 under Debian GNU/Linux. Let me paste my results:
> pairwise.wilcox.test(SAND,Organ,p.adj="bonf") -> a Pairwise comparisons using Wilcoxon rank sum test data: SAND and Organ FlowerA FlowerB FlowerC FlowerD LeafA FlowerB 0.00062 - - - - FlowerC 0.00062 0.00432 - - - FlowerD 0.00062 0.00062 0.00062 - - LeafA 0.00614 0.00614 0.00614 0.00614 - LeafC 0.00062 0.00062 0.00062 0.00062 0.32425 P value adjustment method: bonferroni Warning messages: 1: In wilcox.test.default(xi, xj, ...) : cannot compute exact p-value with ties 2: In wilcox.test.default(xi, xj, ...) : cannot compute exact p-value with ties 3: In wilcox.test.default(xi, xj, ...) : cannot compute exact p-value with ties 4: In wilcox.test.default(xi, xj, ...) : cannot compute exact p-value with ties 5: In wilcox.test.default(xi, xj, ...) : cannot compute exact p-value with ties > multcompLetters(a,Letters=c(letters,LETTERS,".")) Error in do.call(compare, list(x, threshold)) : (list) object cannot be coerced to 'double' I though it was because the bad format of the argument "a" (I think the most similar input may be "A square, symmetric matrix with row names"), so I tried with one valid input produced by a Tukey test (valid as input but not as an analysis of my data because its non-normality) with the aim of checking if this was the problem. > TukeyHSD(aov(SAND~Organ)) -> b Tukey multiple comparisons of means 95% family-wise confidence level Fit: aov(formula = SAND ~ Organ) $Organ diff lwr upr p adj FlowerB-FlowerA -10.392222 -12.12877102 -8.6556734 0.0000000 FlowerC-FlowerA -14.692222 -16.42877102 -12.9556734 0.0000000 FlowerD-FlowerA -5.280000 -7.01654880 -3.5434512 0.0000000 LeafA-FlowerA -3.478889 -5.21543769 -1.7423401 0.0000044 LeafC-FlowerA -2.508889 -4.24543769 -0.7723401 0.0011579 FlowerC-FlowerB -4.300000 -6.03654880 -2.5634512 0.0000000 FlowerD-FlowerB 5.112222 3.37567342 6.8487710 0.0000000 LeafA-FlowerB 6.913333 5.17678453 8.6498821 0.0000000 LeafC-FlowerB 7.883333 6.14678453 9.6198821 0.0000000 FlowerD-FlowerC 9.412222 7.67567342 11.1487710 0.0000000 LeafA-FlowerC 11.213333 9.47678453 12.9498821 0.0000000 LeafC-FlowerC 12.183333 10.44678453 13.9198821 0.0000000 LeafA-FlowerD 1.801111 0.06456231 3.5376599 0.0379548 LeafC-FlowerD 2.771111 1.03456231 4.5076599 0.0002720 LeafC-LeafA 0.970000 -0.76654880 2.7065488 0.5655196 > multcompLetters(b,Letters=c(letters,LETTERS,".")) Error in do.call(compare, list(x, threshold)) : (list) object cannot be coerced to 'double' Además: Warning message: In if (class(x) == "dist") x <- as.matrix(x) : la condición tiene longitud > 1 y sólo el primer elemento será usado (I'm sorry for the spanish warning, it means that the condition has length>1 so only the first element will be used) Any idea of what was the mistake I did? Thank you again! [[alternative HTML version deleted]]
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