[R] using optimize with two unknowns, e.g. to parameterize a distribution with given confidence interval
Hi,
I would like to write a function that finds parameters of a log-normal
distribution with a 1-alpha CI of (x_lcl, x_ucl):
However, I don't know how to optimize for the two unknown parameters.
Here is my unsuccessful attempt to find a lognormal distribution with
a 90%CI of 1,20:
prior - function(x_lcl, x_ucl, alpha, mean, var) {
a - (plnorm(x_lcl, mean, var) - (alpha/2))^2
b - (plnorm(x_ucl, mean, var) - (1-alpha/2))^2
return(a+b)
}
optimize(fn=prior, interval = c(-5, 100), 1, 20)
I understand that this problem has a closed form solution, but I would
like to make this a general function.
Thanks,
David
--
David LeBauer, PhD
Energy Biosciences Institute
University of Illinois Urbana-Champaign
1206 W. Gregory Drive
Urbana, IL 61801, U.S.A.
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Re: [R] can I add line breaks to the paste() function?
Thanks for the help. This solves my problem - I wanted to print out errors and warnings on separate lines with a single call. Thanks, David On Thu, Sep 30, 2010 at 3:42 PM, Jeremy Miles jeremy.mi...@gmail.com wrote: Try using cat instead. Then \n is the new line character. E.g. cat(1st line\n2nd line\n) Jeremy On 30 September 2010 13:30, David LeBauer dleba...@gmail.com wrote: Can I add a line break to the paste() function to return the following: 'this is the first line' 'this is the second line' instead of 'this is the first line this is the second line' ? __ R-help@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. -- Jeremy Miles Psychology Research Methods Wiki: www.researchmethodsinpsychology.com -- David LeBauer, PhD Energy Biosciences Institute University of Illinois Urbana-Champaign 1206 W. Gregory Drive Urbana, IL 61801, U.S.A. __ R-help@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.
[R] can I add line breaks to the paste() function?
Can I add a line break to the paste() function to return the following: 'this is the first line' 'this is the second line' instead of 'this is the first line this is the second line' ? __ R-help@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.
Re: [R] is there a function to find the quantile of the mean of a vector?
Jorge, Thanks for your help. which.min() on the sorted vector divided by the vector length gave me the value I was looking for (I was looking for the probability p(mean(x) | x)): x - runif(1000) x.sort - sort(x) x.length - length(x) x.mean - mean(x) p.mean - which.min((x.sort - x.mean)^2) / x.length Another user pointed out a function suited for this purpose, findInterval() p.mean - findInterval(x.mean, xsort) / x.length Thanks for your help, David On Thu, Jun 17, 2010 at 10:15 PM, Jorge Ivan Velez jorgeivanve...@gmail.com wrote: Hi David, You might try: set.seed(1) x - runif(10, 3, 7) x [1] 4.062035 4.488496 5.291413 6.632831 3.806728 6.593559 6.778701 5.643191 5.516456 3.247145 (x-mean(x))^2 [1] 1.308783661 0.514892188 0.007285983 2.035688832 1.958118177 1.925165288 2.473214156 [8] 0.191087609 0.096348590 3.837329960 which.min((x-mean(x))^2) [1] 3 x[which.min((x-mean(x))^2)] [1] 5.291413 which.min(scale(x, scale = FALSE)**2) [1] 3 See ?which.min and ?scale for more information. HTH, Jorge On Thu, Jun 17, 2010 at 7:06 PM, David LeBauer wrote: Hello, I am interested in finding the quantile of the mean of a vector, something analogous to using the pnorm(), but for an mcmc chain instead of a distribution with known parameters. One approach would be to write a function that finds the index of x_i that minimizes (x-mean(x))^2 I suspect there is a function available to do this, but I can't find it? Thank you, David __ R-help@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. -- David LeBauer, PhD Energy Biosciences Institute University of Illinois Urbana-Champaign 1206 W. Gregory Drive Urbana, IL 61801, U.S.A. __ R-help@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.
[R] is there a function to find the quantile of the mean of a vector?
Hello, I am interested in finding the quantile of the mean of a vector, something analogous to using the pnorm(), but for an mcmc chain instead of a distribution with known parameters. One approach would be to write a function that finds the index of x_i that minimizes (x-mean(x))^2 I suspect there is a function available to do this, but I can't find it? Thank you, David __ R-help@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.
