Re: [R] poisson fit for histogram
Ups! Mr. Ripley is right. I ignored the OS in the posting. My appologies to Tom Isenbarger for the misleading answer. Regards Francisco From: Prof Brian Ripley [EMAIL PROTECTED] To: Francisco J. Zagmutt [EMAIL PROTECTED] CC: [EMAIL PROTECTED], r-help@stat.math.ethz.ch Subject: Re: [R] poisson fit for histogram Date: Sat, 23 Jul 2005 08:29:28 +0100 (BST) What does fit.dist do that fitdistr (MASS) does not in this context? (It plots, but that is very easy to do in base R. However, to see if a Poisson fits you need a test of goodness-of-fit.) BTW, `decompress and store the files in your library folder' is on no OS (you did not mention one but Thomas did) the way to install a package. Even on Windows (where it might just work) there are simpler and better ways to do it, like using a menu. Note that Lindsey does not provide pre-compiled packages for MacOS X, the platform Thomas is using (and as they use Fortran, people have reported that they are tricky to install on MacOS X), and your recipe is `seriously' misleading there. On Fri, 22 Jul 2005, Francisco J. Zagmutt wrote: I would first reccomend you to update your version of R. Then download the libraries rmutil and gnlm from Jim Lindsey at http://www.luc.ac.be/~jlindsey/rcode.html decompress and store the files in your library folder. Sorry but you will have to donwload a package unless you seriously want to re-invent the wheel. Finally try library(gnlm) ?fit.dist() Cheers Francisco From: Thomas Isenbarger [EMAIL PROTECTED] To: r-help@stat.math.ethz.ch Subject: [R] poisson fit for histogram Date: Wed, 20 Jul 2005 10:40:51 -0500 I haven't been an R lister for a bit, but I hope to enlist someone's help here. I think this is a simple question, so I hope the answer is not much trouble. Can you please respond directly to this email address in addition to the list (if responding to the list is warranted)? I have a histogram and I want to see if the data fit a Poisson distribution. How do I do this? It is preferable if it could be done without having to install any or many packages. I use R Version 1.12 (1622) on OS X Thank-you very much, Tom Isenbarger -- Brian D. Ripley, [EMAIL PROTECTED] Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ University of Oxford, Tel: +44 1865 272861 (self) 1 South Parks Road, +44 1865 272866 (PA) Oxford OX1 3TG, UKFax: +44 1865 272595 __ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
Re: [R] poisson fit for histogram
What does fit.dist do that fitdistr (MASS) does not in this context? (It plots, but that is very easy to do in base R. However, to see if a Poisson fits you need a test of goodness-of-fit.) BTW, `decompress and store the files in your library folder' is on no OS (you did not mention one but Thomas did) the way to install a package. Even on Windows (where it might just work) there are simpler and better ways to do it, like using a menu. Note that Lindsey does not provide pre-compiled packages for MacOS X, the platform Thomas is using (and as they use Fortran, people have reported that they are tricky to install on MacOS X), and your recipe is `seriously' misleading there. On Fri, 22 Jul 2005, Francisco J. Zagmutt wrote: I would first reccomend you to update your version of R. Then download the libraries rmutil and gnlm from Jim Lindsey at http://www.luc.ac.be/~jlindsey/rcode.html decompress and store the files in your library folder. Sorry but you will have to donwload a package unless you seriously want to re-invent the wheel. Finally try library(gnlm) ?fit.dist() Cheers Francisco From: Thomas Isenbarger [EMAIL PROTECTED] To: r-help@stat.math.ethz.ch Subject: [R] poisson fit for histogram Date: Wed, 20 Jul 2005 10:40:51 -0500 I haven't been an R lister for a bit, but I hope to enlist someone's help here. I think this is a simple question, so I hope the answer is not much trouble. Can you please respond directly to this email address in addition to the list (if responding to the list is warranted)? I have a histogram and I want to see if the data fit a Poisson distribution. How do I do this? It is preferable if it could be done without having to install any or many packages. I use R Version 1.12 (1622) on OS X Thank-you very much, Tom Isenbarger -- Brian D. Ripley, [EMAIL PROTECTED] Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ University of Oxford, Tel: +44 1865 272861 (self) 1 South Parks Road, +44 1865 272866 (PA) Oxford OX1 3TG, UKFax: +44 1865 272595 __ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
Re: [R] poisson fit for histogram
I would first reccomend you to update your version of R. Then download the libraries rmutil and gnlm from Jim Lindsey at http://www.luc.ac.be/~jlindsey/rcode.html decompress and store the files in your library folder. Sorry but you will have to donwload a package unless you seriously want to re-invent the wheel. Finally try library(gnlm) ?fit.dist() Cheers Francisco From: Thomas Isenbarger [EMAIL PROTECTED] To: r-help@stat.math.ethz.ch Subject: [R] poisson fit for histogram Date: Wed, 20 Jul 2005 10:40:51 -0500 I haven't been an R lister for a bit, but I hope to enlist someone's help here. I think this is a simple question, so I hope the answer is not much trouble. Can you please respond directly to this email address in addition to the list (if responding to the list is warranted)? I have a histogram and I want to see if the data fit a Poisson distribution. How do I do this? It is preferable if it could be done without having to install any or many packages. I use R Version 1.12 (1622) on OS X Thank-you very much, Tom Isenbarger -- Tom Isenbarger PhD [EMAIL PROTECTED] 608.265.0850 [[alternative HTML version deleted]] __ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html __ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
Re: [R] poisson fit for histogram
Hi, see: http://cran.r-project.org/doc/contrib/Ricci-distributions-en.pdf Regards, Vito Thomas Isenbarger isen at plantpath.wisc.edu wrote: I haven't been an R lister for a bit, but I hope to enlist someone's help here. I think this is a simple question, so I hope the answer is not much trouble. Can you please respond directly to this email address in addition to the list (if responding to the list is warranted)? I have a histogram and I want to see if the data fit a Poisson distribution. How do I do this? It is preferable if it could be done without having to install any or many packages. I use R Version 1.12 (1622) on OS X Thank-you very much, Tom Isenbarger -- Tom Isenbarger PhD [EMAIL PROTECTED] 608.265.0850 Diventare costruttori di soluzioni Became solutions' constructors The business of the statistician is to catalyze the scientific learning process. George E. P. Box Statistical thinking will one day be as necessary for efficient citizenship as the ability to read and write H. G. Wells Top 10 reasons to become a Statistician 1. Deviation is considered normal 2. We feel complete and sufficient 3. We are 'mean' lovers 4. Statisticians do it discretely and continuously 5. We are right 95% of the time 6. We can legally comment on someone's posterior distribution 7. We may not be normal, but we are transformable 8. We never have to say we are certain 9. We are honestly significantly different 10. No one wants our jobs Visitate il portale http://www.modugno.it/ e in particolare la sezione su Palese http://www.modugno.it/archivio/palesesanto_spirito/ __ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
[R] poisson fit for histogram
I haven't been an R lister for a bit, but I hope to enlist someone's help here. I think this is a simple question, so I hope the answer is not much trouble. Can you please respond directly to this email address in addition to the list (if responding to the list is warranted)? I have a histogram and I want to see if the data fit a Poisson distribution. How do I do this? It is preferable if it could be done without having to install any or many packages. I use R Version 1.12 (1622) on OS X Thank-you very much, Tom Isenbarger -- Tom Isenbarger PhD [EMAIL PROTECTED] 608.265.0850 [[alternative HTML version deleted]] __ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
Re: [R] poisson fit for histogram
Thomas Isenbarger isen at plantpath.wisc.edu writes: I haven't been an R lister for a bit, but I hope to enlist someone's help here. I think this is a simple question, so I hope the answer is not much trouble. Can you please respond directly to this email address in addition to the list (if responding to the list is warranted)? I have a histogram and I want to see if the data fit a Poisson distribution. How do I do this? It is preferable if it could be done without having to install any or many packages. I use R Version 1.12 (1622) on OS X Thank-you very much, Tom Isenbarger -- Tom Isenbarger PhD isen at plantpath.wisc.edu 608.265.0850 [[alternative HTML version deleted]] __ R-help at stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html by histogram do you mean that you have counts for each non-negative integer? or are the data more binned than that? (I'll assume the former since it's slightly easier to deal with.) Say you have vectors number and count. The mean of the sample is meanval - sum(number*count). The _expected_ number of counts in each bin if the distribution is Poisson is expval - sum(count)*dpois(number,meanval). The chi-square statistic is csq - sum((expval-count)^2/expval), with df - length(count)-2 degrees of freedom (for the mean and the total number of observations). pchisq(csq,df=df,lower.tail=FALSE) should give you the chi-squared probability. A couple of minor issues: (1) beware, this is shooting from the hip -- haven't tested at all; (2) you may have to deal with lumping categories (rule of thumb is that expected number of counts in a bin should not be 5). Other ways to tackle this: use fitdistr() from MASS with different candidate distributions (Poisson, neg. bin.) and do a likelihood ratio test or compare AICs; compare variance and mean of distribution (much cruder). See http://www.zoo.ufl.edu/bolker/emd/probs/ED-4.1.html for a worked example of a similar problem. __ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
Re: [R] poisson fit for histogram
See ?goodfit in package vcd. On 7/20/05, Thomas Isenbarger [EMAIL PROTECTED] wrote: I haven't been an R lister for a bit, but I hope to enlist someone's help here. I think this is a simple question, so I hope the answer is not much trouble. Can you please respond directly to this email address in addition to the list (if responding to the list is warranted)? I have a histogram and I want to see if the data fit a Poisson distribution. How do I do this? It is preferable if it could be done without having to install any or many packages. I use R Version 1.12 (1622) on OS X Thank-you very much, Tom Isenbarger -- Tom Isenbarger PhD [EMAIL PROTECTED] 608.265.0850 [[alternative HTML version deleted]] __ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html __ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
