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copied!<p>One other approach besides kruskal::agricolae mentioned by Marek, is the Nemenyi-Damico-Wolfe-Dunn test implemented in the help page for oneway_test in the coin package that uses multcomp. Using hadley's setup and reducing the B= value for the approximate() function so it finishes in finite time:</p> <pre><code>#updated translation of help page implementation of NDWD NDWD <- independence_test(dv ~ iv, data = sum_codings1, distribution = approximate(B = 10000), ytrafo = function(data) trafo(data, numeric_trafo = rank_trafo), xtrafo = mcp_trafo(iv = "Tukey")) ### global p-value print(pvalue(NDWD)) ### sites (I = II) != (III = IV) at alpha = 0.01 (page 244) print(pvalue(NDWD, method = "single-step")) </code></pre> <p>More stable results on that larger dataset may require increasing the B value and increasing the user's patience.</p> <p>Jan: 2012: There was recently a posting on R-help claiming unexpected results from this method so I forwarded that email to the maintainer. Mark Difford said he had confirmed the problems and offered an alternate tests with the nparcomp package: <a href="https://stat.ethz.ch/pipermail/r-help/2012-January/300100.html" rel="nofollow noreferrer">https://stat.ethz.ch/pipermail/r-help/2012-January/300100.html</a></p> <p>There were also in the same week a couple of other suggestions on rhelp for post-hoc contrasts to KW tests: <a href="https://stat.ethz.ch/pipermail/r-help/2012-January/300316.html" rel="nofollow noreferrer"> kruskalmc suggested by Mario Garrido Escudero </a> and <code>rms::polr</code> followed by <code>rms::contrasts</code> suggested by Frank Harrell <a href="https://stat.ethz.ch/pipermail/r-help/2012-January/300329.html" rel="nofollow noreferrer">https://stat.ethz.ch/pipermail/r-help/2012-January/300329.html</a></p> <p>Nov 2015: Agree with toto_tico that help page code of coin package has been changed in the intervening years. The <code>?independence_test</code> help page now offers a multivariate-KW test and the <code>?oneway_test</code> help page has replace its earlier implementation with the code above usng the <code>independence_test</code> function.</p>

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