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>> 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 >> >> >> >> >> >> > [[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.
