> On Dec 19, 2016, at 1:47 PM, Mauricio Cornejo via R-help > <r-help@r-project.org> wrote: > > Is there a function similar to stats::power.t.test that can handle unequal > variances from two samples? > I noticed that stats::t.test has an argument for indicating whether or not to > treat the two sample variances as equal. Wondering why stats::power.t.test > doesn’t have that option. > Thanks,Mauricio > [[alternative HTML version deleted]]
Because R was developed by statisticians for statisticians and they assumed those other statisticians would know how to extend its functions when needed. But R-help is not advertised as the place to ask such questions when you don't have the statistical skills. (You might want to look at the code of `t.test` to see how you might construct appropriate arguments for `power.t.test` in the situation you imagine. Seems to me it should be fairly straightforward. `power.t.test` is built around the non-central t-distribution and solves a uniroot problem for the missing parameter among n, delta, power, sd, and sig.level, given the other 4 parameters.) -- David Winsemius Alameda, CA, USA ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
