Re: [R] Sample size required to estimate population variance
> Thanks for the suggestion but I'm not sure that it answers my original > question.I need to know how many samples I need to collect to collect in > order to estimate the sample size needed to achieve a specific margin of > error for confidence intervals for the population variance. I'm not sure > whether the pwr package does that. You could consider the case of 50% power, though that'd not be exact for asymmetry. But if this is a simple univariate data set, it sounds like messing around with chi-squared quantiles and uniroot ought to work. Exactly how are you calculating your confidence limits and which one (upper or lower) needs to be of a specific size? *** This email and any attachments are confidential. Any use, copying or disclosure other than by the intended recipient is unauthorised. If you have received this message in error, please notify the sender immediately via +44(0)20 8943 7000 or notify postmas...@lgcgroup.com and delete this message and any copies from your computer and network. LGC Limited. Registered in England 2991879. Registered office: Queens Road, Teddington, Middlesex, TW11 0LY, UK __ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see 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.
Re: [R] Sample size required to estimate population variance
Thanks for the suggestion but I'm not sure that it answers my original question.I need to know how many samples I need to collect to collect in order to estimate the sample size needed to achieve a specific margin of error for confidence intervals for the population variance. I'm not sure whether the pwr package does that. On Thursday, July 4, 2019, 4:31:44 PM PDT, John wrote: On Tue, 2 Jul 2019 22:23:18 + (UTC) Thomas Subia via R-help wrote: > Colleagues, > Can anyone suggest a package or code which might help me calculate > the minimum sample size required to estimate the population variance? > I can do this in Minitab but I'd rather do this in R. Thomas Subia You want to look into the capabilities of the pwr package. This page offers some information: https://www.statmethods.net/stats/power.html JWDougherty [[alternative HTML version deleted]] __ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see 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.
Re: [R] Sample size required to estimate population variance
On Tue, 2 Jul 2019 22:23:18 + (UTC) Thomas Subia via R-help wrote: > Colleagues, > Can anyone suggest a package or code which might help me calculate > the minimum sample size required to estimate the population variance? > I can do this in Minitab but I'd rather do this in R. Thomas Subia You want to look into the capabilities of the pwr package. This page offers some information: https://www.statmethods.net/stats/power.html JWDougherty __ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see 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.
Re: [R] Sample size required to estimate population variance
Hello, Sorry for the HTML, I hadn't realised that my cellphone was not sending in plain text. Rui Barradas Citando ruipbarradas : Hello,Maybe I'm not understanding but to compute the sample variance you need at least 2 data points? The ML estimator can be computed with just 1 but it will be zero.Hope this helps,Rui Barradas Enviado a partir do meu smartphone Samsung Galaxy. Mensagem original De: Thomas Subia via R-help Data: 02/07/2019 23:23 (GMT+00:00) Para: r-help@r-project.org Assunto: [R] Sample size required to estimate population variance Colleagues,Can anyone suggest a package or code which might help me calculate the minimum sample size required to estimate the population variance? I can do this in Minitab but I'd rather do this in R.Thomas Subia [[alternative HTML version deleted]]__r-h...@r-project.org mailing list -- To UNSUBSCRIBE and more, seehttps://stat.ethz.ch/mailman/listinfo/r-helpPLEASE do read the posting guide http://www.R-project.org/posting-guide.htmland provide commented, minimal, self-contained, reproducible code. [[alternative HTML version deleted]] __ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see 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. __ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see 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.
Re: [R] Sample size required to estimate population variance
Hello,Maybe I'm not understanding but to compute the sample variance you need at least 2 data points? The ML estimator can be computed with just 1 but it will be zero.Hope this helps,Rui Barradas Enviado a partir do meu smartphone Samsung Galaxy. Mensagem original De: Thomas Subia via R-help Data: 02/07/2019 23:23 (GMT+00:00) Para: r-help@r-project.org Assunto: [R] Sample size required to estimate population variance Colleagues,Can anyone suggest a package or code which might help me calculate the minimum sample size required to estimate the population variance? I can do this in Minitab but I'd rather do this in R.Thomas Subia [[alternative HTML version deleted]]__r-h...@r-project.org mailing list -- To UNSUBSCRIBE and more, seehttps://stat.ethz.ch/mailman/listinfo/r-helpPLEASE do read the posting guide http://www.R-project.org/posting-guide.htmland provide commented, minimal, self-contained, reproducible code. [[alternative HTML version deleted]] __ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see 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.
Re: [R] Sample size required to estimate population variance
Does this help? https://www.r-bloggers.com/computing-sample-size-for-variance-estimation/ On Wed, 3 Jul 2019 at 10:23, Thomas Subia via R-help wrote: > Colleagues, > Can anyone suggest a package or code which might help me calculate the > minimum sample size required to estimate the population variance? I can do > this in Minitab but I'd rather do this in R. > Thomas Subia > [[alternative HTML version deleted]] > > __ > R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see > 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. > [[alternative HTML version deleted]] __ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see 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.
[R] Sample size required to estimate population variance
Colleagues, Can anyone suggest a package or code which might help me calculate the minimum sample size required to estimate the population variance? I can do this in Minitab but I'd rather do this in R. Thomas Subia [[alternative HTML version deleted]] __ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see 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.
