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? 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%. Thank yoou [[alternative HTML version deleted]]
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 orifs.> > 1st Question > My first question is that I have generated 100 random numbers from the uniformdistribution 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 offreedom 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
Siterer "Sascha Vieweg" <saschaview at gmail.com>:> On 11-01-27 14:24, Ben Bolker wrote: > >> Ben Boyadjian <benjy_cy_21 <at> hotmail.com> writes: > > Double post? >Yes, probably just hoped that if he changed the subject someone would do his homework for him...
On 11-01-27 14:24, Ben Bolker wrote:> Ben Boyadjian <benjy_cy_21 <at> hotmail.com> writes:Double post?>> 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?x <- c(1, 1.3) x==round(x, 0)> 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: ?rtRather ugly and long winded, but works: z <- rt(1000, 3) q <- quantile(z, c(.05, .95)) mean(z[z>q[1] & z<q[2]])> > good luck, > Ben Bolker > > ______________________________________________ > R-help at 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. >-- Sascha Vieweg, saschaview at gmail.com
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 [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" <bbolker at gmail.com> > Sent: Thursday, January 27, 2011 2:24 PM > To: <r-help at 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 at 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-----