> -----Original Message----- > From: r-help-boun...@r-project.org [mailto:r-help-bounces@r- > project.org] On Behalf Of jlu...@ria.buffalo.edu > Sent: Tuesday, September 30, 2014 11:49 AM > To: Andre > Cc: r-help@r-project.org > Subject: Re: [R] Inverse Student t-value > > My Excel (2013) returns exactly what R does. I used both T.INV and > T.INV.T2 There is no TINV. Has Excel been updated? > >
I have Excel 2007, and it does have the function TINV(). And, it also returns the same value as R-3.1.1. So, there appears to be a problem with whatever unstated system and version of Excel that the OP is using. Dan Daniel J. Nordlund Research and Data Analysis Division Services & Enterprise Support Administration Washington State Department of Social and Health Services > > > > Duncan Murdoch <murdoch.dun...@gmail.com> > Sent by: r-help-boun...@r-project.org > 09/30/2014 02:36 PM > > To > Andre <geomodel...@gmail.com>, > cc > r-help@r-project.org > Subject > Re: [R] Inverse Student t-value > > > > > > > On 30/09/2014 2:26 PM, Andre wrote: > > Hi Duncan, > > > > Actually, I am trying trace the formula for the "Critical value of Z" > > and manual formula is > > =(I7-1)/SQRT(I7)*SQRT((TINV(0.05/I7,I7-2))^2/(I7-2+TINV(0.05/I7,I7- > 2))) > > > > So, I got new problem for TINV formula. I just need a manual equation > > for TINV. > > Sorry, can't help. I'm not sure I understand what you want, but if > it's > a simple formula for quantiles of the t distribution, it doesn't exist. > > Duncan Murdoch > > > > > Hope solve this problem. > > > > Cheers! > > > > > > On Wed, Oct 1, 2014 at 1:20 AM, Duncan Murdoch > > <murdoch.dun...@gmail.com <mailto:murdoch.dun...@gmail.com>> wrote: > > > > On 30/09/2014 2:11 PM, Andre wrote: > > > > Hi Duncan, > > > > No, that's correct. Actually, I have data set below; > > > > > > Then it seems Excel is worse than I would have expected. I > > confirmed R's value in two other pieces of software, > > OpenOffice and some software I wrote a long time ago based on an > > algorithm published in 1977 in Applied Statistics. (They are > > probably all using the same algorithm. I wonder what Excel is > doing?) > > > > N= 1223 > > alpha= 0.05 > > > > Then > > probability= 0.05/1223=0.0000408831 > > degree of freedom= 1223-2= 1221 > > > > So, TINV(0.0000408831,1221) returns 4.0891672 > > > > > > Could you show me more detail a manual equation. I really > > appreciate it if you may give more detail. > > > > > > I already gave you the expression: abs(qt(0.0000408831/2, > > df=1221)). For more detail, I suppose you could look at the help > > page for the qt function, using help("qt"). > > > > Duncan Murdoch > > > > > > Cheers! > > > > > > On Wed, Oct 1, 2014 at 1:01 AM, Duncan Murdoch > > <murdoch.dun...@gmail.com <mailto:murdoch.dun...@gmail.com> > > <mailto:murdoch.dun...@gmail.com > > <mailto:murdoch.dun...@gmail.com>>> wrote: > > > > On 30/09/2014 1:31 PM, Andre wrote: > > > > Dear Sir/Madam, > > > > I am trying to use calculation for two-tailed inverse > > of the > > student`s > > t-distribution function presented by Excel functions > like > > =TINV(probability, deg_freedom). > > > > For instance: The Excel function > > =TINV(0.0000408831,1221) = returns > > 4.0891672. > > > > Would you like to show me a manual calculation for > this? > > > > Appreciate your helps in advance. > > > > > > That number looks pretty far off the true value. Have you > > got a > > typo in your example? > > > > You can compute the answer to your question as > > abs(qt(0.0000408831/2, df=1221)), but you'll get 4.117. > > > > Duncan Murdoch > > > > > > > > > > > > ______________________________________________ > 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. > > > [[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. ______________________________________________ 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.