[R] Writing program for these

Sascha Vieweg saschaview at gmail.com
Thu Jan 27 15:36:58 CET 2011

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: ?rt

Rather 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
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Sascha Vieweg, saschaview at gmail.com

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