wow, thanks for the informative inputs! I'm glad I post that silly question..thanks!
On Wed, Oct 17, 2012 at 6:51 PM, Greg Snow <538...@gmail.com> wrote: > Rui answered the main question by pointing out that you need z.test(m, > stdev=s(m)), or you could use z.test(m,,sd(m)), but I think the stdev= > approach is clearer. But you are really abusing the concept of z > tests in general (and the z.test function in particular) by using the > sd of the sample. If you use the sd of the sample then you should be > doing a t test (and the t.test function does this simpler than the > z.test function). The z.test function was designed to use in classes > that introduce the concepts of inference using the generally > unrealistic (but simpler) case of knowing the population standard > deviation, but not the mean. The z.test function was to be a bridge > so that the students could use a function that was similar to the > t.test function that they would eventually use. > > On Wed, Oct 17, 2012 at 12:45 AM, Balqis <aehan3...@gmail.com> wrote: > > Hi! > > I'm trying to use sapply to my dataframe for z.test function (teaching > > demos package) > > > > > > Sep=cbind(kIp,k02p,k04p,k07p) > > Sep=as.data.frame(Sep) > > > > kzt=sapply(Sep, function(m) z.test(m,sd(m))) > > Error in z.test(m, sd(Sep)) : > > You must specify a Standard Deviation of the population > > > > kzt=sapply(Sep, function(m) z.test(m,sd(Sep))) > > Error in z.test(m, sd(Sep)) : > > You must specify a Standard Deviation of the population > > > > #obviously it can't process the z.test because of the sd function > embedded > > inside the function. can someone point me how to fix this. Many thanks! > > > > [[alternative HTML version deleted]] > > > > ______________________________________________ > > 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. > > > > -- > Gregory (Greg) L. Snow Ph.D. > 538...@gmail.com > [[alternative HTML version deleted]] ______________________________________________ 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.
