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.
sample mean, variance and SD
10 messages · parvez_200207, Greg Snow, Berend Hasselman +4 more
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On 10-11-2012, at 21:09, Greg Snow 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?
Probably.
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?
I would tend to agree with the last paragraph. Berend
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.
-- Gregory (Greg) L. Snow Ph.D. 538280 at gmail.com [[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.
On 10-11-2012, at 19:23, 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.
What is your actual question? You have calculated what you were supposed to. I guessing that the result wasn't what you expected. I'm not going to give you a ready made answer to a question you didn't ask. In an R console do ?rweibull and read carefully about the shape and scale arguments in the Details section. That should help you to understand your results. Berend
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 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.
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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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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:
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.
On 11/11/2012 07:09 AM, Greg Snow 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? ...
As usual, a thoughtful comment on a problem that does not have a straightforward solution. The actual responses to obvious homework questions range from curt refusals to worked examples. I don't know the official status of the "no homework" policy if there is one. My responses are guided by their expected utility. If the question appears to be asked by someone who has just gotten stuck on an esoteric quirk of R (and the extraction operators are a good example), I'll try to get them over the hump. In this particular case, parvez_200207 seems to have answered the question and not realized it. Maybe this was due to something that parvez_200207 didn't even know was going on (e.g. a sink() was operating) or maybe it was just complete cluelessness. If I strongly suspected the former, I probably would have answered. Jim
On Nov 10, 2012, at 6:58 PM, Jim Lemon wrote:
On 11/11/2012 07:09 AM, Greg Snow 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? ...
As usual, a thoughtful comment on a problem that does not have a straightforward solution. The actual responses to obvious homework questions range from curt refusals to worked examples. I don't know the official status of the "no homework" policy if there is one.
The fourth entry (very close to the top) in the Posting Guide says: "<b>Basic statistics and classroom homework:</b> R-help is not intended for these."
My responses are guided by their expected utility. If the question appears to be asked by someone who has just gotten stuck on an esoteric quirk of R (and the extraction operators are a good example), I'll try to get them over the hump.
That's been my approach as well. I may simply offer: ?<func-name> ... but if they merely post an obvious homework problem with no effort visible I will either ignore it or point to the Posting Guide. Sometimes a preamble along the lines of "I tried to do this and cannot get academic support because the teacher is using SAS" will be sufficiently convincing.
In this particular case, parvez_200207 seems to have answered the question and not realized it.
I wondered whether parvez_200207 wanted to do the same procedure 1000 times and record the summary statistics each time.
Maybe this was due to something that parvez_200207 didn't even know was going on (e.g. a sink() was operating) or maybe it was just complete cluelessness. If I strongly suspected the former, I probably would have answered.
David Winsemius, MD Alameda, CA, USA