Hi JLucke, Maybe the old excel function. TINV and T.INV.2T is same function for Two-Tailed Inverse of the student`s t-distribution but T.INV use for Left-Tailed inverse of the Student's t-distribution and can be use for Inverse of the student`s t-distribution.
I know automatic or functions any software but I just need a manual formula or compute formula (TINV or T.INV.2T) step by step presented by math for calculate until resulted. Thanks in advance. Cheers! On Wed, Oct 1, 2014 at 2:39 AM, <jlu...@ria.buffalo.edu> wrote: > The website has your answer. The t-distribution is a regularized > incomplete beta function. The incomplete beta function is given by R's > *pbeta* function. You regularize it with R's *beta* function. Then you > use R's *uniroot* function to find the inverse. Good homework problem. > > > *Andre <geomodel...@gmail.com <geomodel...@gmail.com>>* > Sent by: r-help-boun...@r-project.org > > 09/30/2014 02:45 PM > To > Duncan Murdoch <murdoch.dun...@gmail.com>, > cc > "r-help@r-project.org" <r-help@r-project.org> > Subject > Re: [R] Inverse Student t-value > > > > > Hi Duncan, > > Let me explain again, I just need a manual expression for inverse student t > value. > > You could go to web page > http://www.danielsoper.com/statcalc3/calc.aspx?id=10 > > That's inverse student t value calculator. Do you know a manual expression > use it. > > Cheers! > > > On Wednesday, October 1, 2014, Duncan Murdoch <murdoch.dun...@gmail.com> > wrote: > > > 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 <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 > <murdoch.dun...@gmail.com>> > >> <mailto:murdoch.dun...@gmail.com <murdoch.dun...@gmail.com> > >> <mailto:murdoch.dun...@gmail.com <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 > >> > >> > >> > >> > >> > >> > > > > [[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 > <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.
