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[cc'ing back to r-help] On 01/27/2011 10:06 AM, Ben Boyadjian wrote: > Yes the it says the uniform distribution on the interval (-5,5). If this is real-valued (which again is not precisely defined, but that would be how I would interpret) then the probability of choosing an integer is again zero. With double-precision floating point values it is not zero but is extremely small. > > This is what I have done for Question 2 > There is the trim function that can give the answer but I am meant to > write the program. My question is whether I use the 0.05 or the 0.1. I > dont want anything below the 5% and above the 95%. Why not look at ?mean for the answer? Or compare the answer from using mean with the 'trim' argument to the alternative solution you listed below? > > # We first simulate 1000 observations ..... > > x<-rt(1000,3) > mean(x,trim=0.05) #or 0.1 I am not sure > z<-sort(x) > #next use either > y<-z[-c(1:50,951:1000)] # We want the bottom 5% and top 5% so this > corresponds to the elements that we are taking away. > #or > #y<-z[-c(1:100,901:1000)] > mean(y) > > -------------------------------------------------- > From: "Ben Bolker" <bbol...@gmail.com> > Sent: Thursday, January 27, 2011 2:24 PM > To: <r-h...@stat.math.ethz.ch> > Subject: Re: [R] Writing program for these > >> Ben Boyadjian <benjy_cy_21 <at> hotmail.com> writes: >> >>> >>> Hello I am trying to solve these problems and I am not allowed to use >>> loops or >> ifs. >>> >>> 1st Question >>> My first question is that I have generated 100 random numbers from >>> the uniform >> distribution then >>> A)add only the negative integers. >>> B)add elements until the first appearance of a negative element. >>> >>> I know how to choose the negative elements for A but how to find >>> integers? >> >> If this is the standard uniform U(0,1) distribution (which I assume >> from your phrase "*the* uniform distribution" (emphasis added)) >> then there will be no integers in the sample ... ?? >> >>> And I dont know what to do for B. >>> >>> 2nd Question >>> Simulate 1000 observations from the student-t distribution with 3 >>> degrees of >> freedom and then calculate >>> the truncated mean by excluding bottom 5% and top 5%. >> >> Looks like homework questions, which are not answered on this list. >> Please read the posting guide; if these are *not* homework questions, >> please give us a plausible context. (Even if these are not homework >> questions, the posting guide asks that you "do your homework" in a >> broader sense by indicating what steps you have taken to solve your >> problem on your own before posting.) >> >> One hint for the second question: ?rt >> >> good luck, >> Ben Bolker >> >> ______________________________________________ >> 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. >> -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.10 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iEYEARECAAYFAk1Bja0ACgkQc5UpGjwzenMf4wCeOsJ0uxMn5nOdUbAhJzrl8CHU uj8AniPodV2HAwA6Cqi8Hpm/0ANh+yQ1 =mTtk -----END PGP SIGNATURE----- ______________________________________________ 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.
