Thanks for your responses. I know it is bad form asking about these things but i was really having trouble getting my head around it, and i wanted to make sure that the cause wasn't due to the commands i was entering into R. At least now i know it's a conceptual error i am making rather than a technical one.
Thanks again for your help. R. Duncan Murdoch-2 wrote: > > On 10/16/2008 7:35 AM, Peter Dalgaard wrote: >> rr400 wrote: >>> Hi, i am doing a statistics course and am having trouble with an >>> exercise >>> where i need to determine whether my success rate at something is higher >>> than 80%. >>> I was successful in 29 out of 60 trials, so these were the commands i >>> entered into R: >>>> n=60 >>>> p.hat=29/n >>>> p.0=0.8 >>>> se.0=sqrt(p.0*(1-p.0)/n) >>>> z=(p.hat-p.0)/se.0 >>>> print(z) >>> Which returned: >>> [1] -6.132224 >>>> 1-pnorm(z) >>> Which returned >>> [1] 1 >>> >>> My problem is that i am meant to state a null and alternative hypothesis >>> which at the moment i have stated as p>0.8 (null) and p≤0.8 >>> (alternative). >>> As things stand, though, a p-value of 1 suggests i should reject the >>> null >>> hypothesis which can't be right since i am obviously successful less >>> than >>> 80% of the time. >>> I am not sure where i am getting muddled. Any advice would be greatly >>> appreciated. Thanks! >> >> This isn't really about R, and maybe it is homework, but now that we got >> you in the appropriate frame of mind: >> >> (a) p values should look at "this or more unfavourable" events. You have >> arranged things so that that translates to -6.13 or _lower_. I.e. you're >> looking at the wrong tail. > > I think he was looking at the right tail, since his p value was 1. Your > comment (b) is the important one; comment (c) might not be allowed by > his instructor, which is one reason I'm always reluctant to give advice > on other people's homework problems. > > Duncan Murdoch > >> >> (b) Make sure you get your accept/reject logic right. You _reject_ the >> null when data would be _un_likely if the null hypothesis were true. >> >> (c) You might also want to play with binom.test and prop.test >> > > ______________________________________________ > 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. > > -- View this message in context: http://www.nabble.com/One-sample-test-for-p-tp20010677p20012878.html Sent from the R help mailing list archive at Nabble.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.
