On Jun 24, 2013, at 15:21 , Sarah Goslee wrote: > G'morning. > > On Mon, Jun 24, 2013 at 2:22 AM, peter dalgaard <pda...@gmail.com> wrote: >> >> On Jun 23, 2013, at 22:30 , Sarah Goslee wrote: >> >>> Hi, >>> >>> If you're doing exactly as described below, then you need to add the >>> data argument to wilcox.test so R knows where to find beforesmall and >>> aftersmall. But if so, that's a rather uninformative error message. >>> >>> Saraj >> >> Not really, if you use the formula interface, the rhs is supposed to be the >> grouping, as in >> >> wilcox.test(extra ~ group, data=sleep, paired=TRUE) >> >> so it's telling you that "aftersmall" does not describe two groups. > > Yep, sorry. That was actually my first thought, but then I misread the > helpfile. > > You do still need the data argument, though. :)
-- or a preceding attach(), which at least some of us still use occasionally despite its dangers. For paired tests, it doesn't actually work to use data=, you need with(mydata, t.test(beforesmall, aftersmall, paired=TRUE)) -pd > > Sarah > >> (It is unfortunate, though, that we don't have a formula interface to the >> parallel-vector data layout for paired tests. That is the common case, the >> sleep data set is a rather rare exception. A formula specification for >> paired columns has been talked about; something like cbind(before, after) ~ >> 1 should be workable, but nothing has materialized to date.) >> >> -pd >> >>> >>> On Sun, Jun 23, 2013 at 2:34 PM, ruth parker <parkeractonr...@gmail.com> >>> wrote: >>>> Hi, >>>> I've been trying to run a wilcox paired test on some data >>>> beforesmall aftersmall >>>> [1,] 63.5 512.0 >>>> [2,] 54.5 237.5 >>>> [3,] 52.5 161.5 >>>> [4,] 78.0 153.5 >>>> [5,] 53.5 68.0 >>>> [6,] 50.5 65.5 >>>> [7,] 69.0 52.0 >>>> [8,] 76.0 59.0 >>>> [9,] 68.0 66.5 >>>> [10,] 75.5 66.5 >>>> [11,] 67.0 45.5 >>>> [12,] 81.0 54.5 >>>> [13,] 49.0 44.0 >>>> [14,] 51.0 42.5 >>>> [15,] 53.0 34.5 >>>> >>>> using >>>> wilcox.test(beforesmall ~ aftersmall,paired=T) >>>> but I get the error message: >>>> >>>> Error in wilcox.test.formula(beforesmall ~ aftersmall, paired = T) : >>>> grouping factor must have exactly 2 levels >>>> >>>> I don't have any missing values, I have the same amount of data points for >>>> each group and I've looked everywhere trying to find the answer. >>>> Please can somebody tell me how to make it work >>>> thanks >>>> >>> > > > -- > Sarah Goslee > http://www.functionaldiversity.org > > ______________________________________________ > R-help@r-project.org mailing list > 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. -- Peter Dalgaard, Professor, Center for Statistics, Copenhagen Business School Solbjerg Plads 3, 2000 Frederiksberg, Denmark Phone: (+45)38153501 Email: pd....@cbs.dk Priv: pda...@gmail.com ______________________________________________ R-help@r-project.org mailing list 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.
