Hello, when performing the wilcox.test on a sample (n=100) with the following frequency distribution: Value | Frequency ---------------------------------------- 0 | 10 0.1 | 88 1 | 1 2.6 | 1 I get the following error message: Error in uniroot(wdiff, c(mumin, mumax), tol = 1e-04, zq = qnorm(alpha/2, : f() values at end points not of opposite sign The error only occurs when I specify that the confidence interval should be computed. Could anybody suggest how I can compute the confidence interval for this sample? Is the problem connected with the large number of ties and if so, how can I handle these ties? Thanks in advance. Regards Chris -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", or "[un]subscribe" (in the "body", not the subject !) To: r-help-request at stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._
"Swanepoel, Christiaan Edward" wrote:> > Hello, > > when performing the wilcox.test on a sample (n=100) with the following frequency distribution: > Value | Frequency > ---------------------------------------- > 0 | 10 > 0.1 | 88 > 1 | 1 > 2.6 | 1 > > I get the following error message: > > Error in uniroot(wdiff, c(mumin, mumax), tol = 1e-04, zq = qnorm(alpha/2, : > f() values at end points not of opposite sign > > The error only occurs when I specify that the confidence interval should be computed. > > Could anybody suggest how I can compute the confidence interval for this sample? Is the problem connected with the large number of ties and if so, how can I handle these ties?You could look inti the package exactRankTests. Kjetil Halvorsen> > Thanks in advance. > > Regards > Chris > > -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- > r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html > Send "info", "help", or "[un]subscribe" > (in the "body", not the subject !) To: r-help-request at stat.math.ethz.ch > _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", or "[un]subscribe" (in the "body", not the subject !) To: r-help-request at stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._
On 19 Jul 2002, at 15:16, Swanepoel, Christiaan Edward wrote:> Hello, > > when performing the wilcox.test on a sample (n=100) with the following > frequency distribution: Value | Frequency > ---------------------------------------- 0 | 10 0.1 | 88 1 | 1 2.6 | 1 > > I get the following error message: > > Error in uniroot(wdiff, c(mumin, mumax), tol = 1e-04, zq > qnorm(alpha/2, : > f() values at end points not of opposite sign > > The error only occurs when I specify that the confidence interval > should be computed. > > Could anybody suggest how I can compute the confidence interval for > this sample? Is the problem connected with the large number of ties > and if so, how can I handle these ties?>From the help:"By default (if exact is not specified), an exact p-value is computed if the samples contain less than 50 finite values and there are no ties. Otherwise, a normal approximation is used." The error message tells that a normal approximation is being attempted. On the other hand, I would rather not rely on a normal approximation here. With so few observations differing from 0.1, a hand computation might be easy for a high confidence level. In general, for the correct handling of ties entering data like yours as round( x, 1) can be tried.> Thanks in advance. > > Regards > Chris > > -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-. > -.-.-.-.- r-help mailing list -- Read > http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", > or "[un]subscribe" (in the "body", not the subject !) To: > r-help-request at stat.math.ethz.ch > _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._. > _._._._._Timo Timo Makelainen, Department of Mathematics University of Helsinki, P.O. Box 4 FIN-00014 Helsinki Tel.: +358-9-19122863 Fax: +358-9-19123213 E-mail: Timo.Makelainen at Helsinki.Fi -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", or "[un]subscribe" (in the "body", not the subject !) To: r-help-request at stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._
On 19 Jul 2002, at 18:59, Timo M?kel?inen wrote:> On 19 Jul 2002, at 15:16, Swanepoel, Christiaan Edward wrote: > > > Hello, > > > > when performing the wilcox.test on a sample (n=100) with the > > following frequency distribution: Value | Frequency > > ---------------------------------------- 0 | 10 0.1 | 88 1 | 1 > > 2.6 | 1 > > > > I get the following error message: > > > > Error in uniroot(wdiff, c(mumin, mumax), tol = 1e-04, zq > > qnorm(alpha/2, : > > f() values at end points not of opposite sign > > > > The error only occurs when I specify that the confidence interval > > should be computed. > > > > Could anybody suggest how I can compute the confidence interval for > > this sample? Is the problem connected with the large number of ties > > and if so, how can I handle these ties? > > >From the help: > > "By default (if exact is not specified), an exact p-value is computed > if the samples contain less than 50 finite values and there are no > ties. Otherwise, a normal approximation is used." > > The error message tells that a normal approximation is being > attempted.Suggesting that some ties have been correctly recognised. On the other hand, I would rather not rely on a normal> approximation here. With so few observations differing from 0.1, a > hand computation might be easy for a high confidence level. > > In general, for the correct handling of ties entering data like yours > as round( x, 1) can be tried.Better, look at the code to see how they are handled.> > Thanks in advance. > > > > Regards > > Chris > > > > -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-. > > -. -.-.-.-.- r-help mailing list -- Read > > http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", > > or "[un]subscribe" (in the "body", not the subject !) To: > > r-help-request at stat.math.ethz.ch > > _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._. > > _. _._._._._ > > Timo > > > Timo Makelainen, Department of Mathematics > University of Helsinki, P.O. Box 4 > FIN-00014 Helsinki > Tel.: +358-9-19122863 > Fax: +358-9-19123213 > E-mail: Timo.Makelainen at Helsinki.Fi > -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-. > -.-.-.-.- r-help mailing list -- Read > http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", > or "[un]subscribe" (in the "body", not the subject !) To: > r-help-request at stat.math.ethz.ch > _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._. > _._._._._Timo Timo Makelainen, Department of Mathematics University of Helsinki, P.O. Box 4 FIN-00014 Helsinki Tel.: +358-9-19122863 Fax: +358-9-19123213 E-mail: Timo.Makelainen at Helsinki.Fi -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", or "[un]subscribe" (in the "body", not the subject !) To: r-help-request at stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._