[R] sample mean, variance and SD

[Jeff Newmiller]

It is not always easy to discern what the instructor wants a student to get out of an assignment. Therefore, I can't see changing the policy as it stands.

 That said, it is not always easy to discern homework from self-study, and sometimes when the question is well-constructed I don't go out of my way to confirm whether it is homework... the instructor has internet access too.
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Sent from my phone. Please excuse my brevity.

Greg Snow <538280 at gmail.com> wrote:

>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
>> >
>> >
>> >
>> > --
>> > View this message in context:
>> >
>http://r.789695.n4.nabble.com/sample-mean-variance-and-SD-tp4649190.html
>> > Sent from the R help mailing list archive at Nabble.com.
>> >
>> > ______________________________________________
>> > R-help at r-project.org <javascript:;> 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.
>> >
>>
>>
>> --
>> Sarah Goslee
>> http://www.stringpage.com
>> http://www.sarahgoslee.com
>> http://www.functionaldiversity.org
>>
>>         [[alternative HTML version deleted]]
>>
>> ______________________________________________
>> 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.
>>