sample mean, variance and SD

This is to all R-helpers (Sarah is just the one that I am replying to),

Have we become a little too draconian on the "not a homework help list"
issue?

Now if someone just states the HW question, gives no indication that
they
have done anything to try to solve it themselves, and expects us to
give
them a completed answer without effort on their part, I am happy to
light
up the flame thrower (and if they are my students they could very well
lose
points for poor questions).  But I think there are cases where it is
reasonable for us to help point students in the right direction (at our
own discretion, but without a knee jerk "no homework" response).  Some
of
the types of questions that we have seen on this list that I think
would
qualify here would include things like:

I already turned in my homework after using <program other than R> that
the
teacher uses, but now I would like to learn how to do it in R as well,
can
anyone give me pointers to which help page(s) I should read to learn
how to
do <topic>.

My teacher says we can use any program we want and I chose R, but the
teacher and TA's don't know R, I have figured out most of this problem
<problem statement and code tried so far>, but I can't figure out how
to do
this last part, any pointers?

I fit this model <model info> to the HW data using <R commands> and
these
are the results that I see <results>, but the answer in the book while
matching on some things has a different value for these coefficients
<list
with other numbers>.  I am thinking that R must be using a different
default or encoding than the book, can anyone explain the reason for
the
difference or give a pointer to where it is documented?

And other cases where a student is clearly doing homework, but shows
that
they have made an effort on their own and is not demanding we do the
work
for them, but would rather like a pointer or hint to help them learn
better.  I vote that we adopt a policy (unofficial) that if a student
shows
effort and asks a reasonable question that we respond with answers that
will help the student continue to learn (and become a better member of
the
R community).  What do others think?


On Sat, Nov 10, 2012 at 11:40 AM, Sarah Goslee
<sarah.goslee at gmail.com>wrote:

This is not a homework help list.

On Saturday, November 10, 2012, parvez_200207 wrote:

hi
could you help me to solve this issue

Question:
Using command rweibull(100,8,15), simulate n = 100 realizations

from

Weibull(8; 15) distribution. Using the simulated sample, compute

the

sample

mean, variance and standard deviation of these observations.

I am trying like this

sim<-rweibull(100,8,15) # simulated sample
SM<-mean(sim) # simulated sample mean
var(sim)      # variance
sd(sim)       #SD

Thank you in advance.

Parvez



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Sarah Goslee
http://www.stringpage.com
http://www.sarahgoslee.com
http://www.functionaldiversity.org

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