That seems great to me. Thank you very much! -Thomas
On Sat, Feb 23, 2019 at 11:14 AM Martin Maechler <maech...@stat.math.ethz.ch> wrote: > > >>>>> peter dalgaard > >>>>> on Fri, 22 Feb 2019 12:38:14 +0100 writes: > > > It's not a problem per se to put additional information > > into class htest objects (hey, it's S3 after all...) and > > there is a precedent in chisq.test which returns $observed > > and $expected. > > It seems the consent is to simply return the SE but *not* change > the print() method, and also be careful not to mess with > existing parts of the result. > So, a minimal patch is to add the short line > > stderr = stderr, > > inside the list(..) constucting the return value... > > and that's what I'm planning to commit (to the sources). > > With thanks for the suggestion and considerations to > Thomas, John and Peter! > > Martin > > > Getting such information printed by print.htest is more tricky, > although it might be possible to (ab)use the $estimate slot. > > > The further question is whether one would really want to do that > (change the output and/or modify the current return values), at the risk of > affecting a rather large bundle of existing scripts, books, lecture notes, > etc. I don't think that I would want to do that for the case of the s.e.d., > although I'll admit that there is another thing that has always been a bit of > an eyesore to me: We give a confidence interval but not the corresponding > point estimate (i.e. the _difference_ of the means). > > > It might be better to simply start over and write a new function. In > the process one might address other things that people have been asking for, > like calculations based on the sample mean and SDs (which would useful for > dealing with published summaries and textbook examples). Oh, and a formula > interface for the one-sample test. > > > -pd > > >> On 21 Feb 2019, at 22:51 , Fox, John <j...@mcmaster.ca> wrote: > >> > >> Dear Thomas, > >> > >> it is, unfortunately, not that simple. t.test() returns an object of > class "htest" and not all such objects have standard errors. I'm not entirely > sure what the point is since it's easy to compute the standard error of the > difference from the information in the object (adapting an example from > ?t.test): > >> > >>> (res <- t.test(1:10, y = c(7:20))) > >> > >> Welch Two Sample t-test > >> > >> data: 1:10 and c(7:20) > >> t = -5.4349, df = 21.982, p-value = 1.855e-05 > >> alternative hypothesis: true difference in means is not equal to 0 > >> 95 percent confidence interval: > >> -11.052802 -4.947198 > >> sample estimates: > >> mean of x mean of y > >> 5.5 13.5 > >> > >>> as.vector(abs(diff(res$estimate)/res$statistic)) # SE > >> [1] 1.47196 > >>> class(res) > >> [1] "htest" > >> > >> and if you really want to print the SE as a matter of course, you > could always write your own wrapper for t.test() that returns an object of > class, say, "t.test" for which you can provide a print() method. Much of the > advantage of working in a statistical computing environment like R (or Stata, > for that matter) is that you can make things work the way you like. > >> > >> Best, > >> John > >> > >> ------------------------------------------------- > >> John Fox, Professor Emeritus > >> McMaster University > >> Hamilton, Ontario, Canada > >> Web: http::/socserv.mcmaster.ca/jfox > >> > >>> On Feb 21, 2019, at 3:57 PM, Thomas J. Leeper <thosjlee...@gmail.com> > wrote: > >>> > >>> A recent thread on Twitter [1] by a Stata user highlighted that > t.test() > >>> does not return or print the standard error of the mean difference, > despite > >>> it being calculated by the function. > >>> > >>> I know this isn’t the kind of change that’s likely to be made but > could we > >>> at least return the SE even if the print() method isn’t updated? Or, > >>> better, update the print() method to display this as well? > >>> > >>> Best, > >>> Thomas > >>> > >>> [1] > >>> https://twitter.com/amandayagan/status/1098314654470819840?s=21 > >>> -- > >>> > >>> Thomas J. Leeper > >>> http://www.thomasleeper.com > >>> > >>> [[alternative HTML version deleted]] > >>> > >>> ______________________________________________ > >>> R-devel@r-project.org mailing list > >>> https://stat.ethz.ch/mailman/listinfo/r-devel > >> > >> ______________________________________________ > >> R-devel@r-project.org mailing list > >> https://stat.ethz.ch/mailman/listinfo/r-devel > > > -- > > Peter Dalgaard, Professor, > > Center for Statistics, Copenhagen Business School > > Solbjerg Plads 3, 2000 Frederiksberg, Denmark > > Phone: (+45)38153501 > > Office: A 4.23 > > Email: pd....@cbs.dk Priv: pda...@gmail.com > > > ______________________________________________ > > R-devel@r-project.org mailing list > > https://stat.ethz.ch/mailman/listinfo/r-devel ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
