search for: statistcal

Dear friends, As we all know, the usual model selection criteria(e.g.deviance,AIC...) in GLMs isn't very good for selecting the best model when overdispersion exist, so we need to adjust the corresponding statistic,see(Fitzmaurice,G.M. (1997) Model selection with overdispersed

I have a binary file(a) with size of (360 720 )for the globe.I wrote the code given below to read and extract an area (south america)from that file. when I use summary for the whole file I got: summary(a, na.rm=FALSE) Min. 1st Qu. Median Mean 3rd Qu. Max. NA's 0.00 1.00 3.00 4.15 7.00 20.00 200083 . But when I used summary for the region(b) which I extracted, I got

...C i.e. We are hypothesising that C is the effect and either A or B, not both is the cause. i.e. A causes C and this cause-effect relationship explains B. The data for A contains more noise than that for B. We are working with around 1000 points. I would greatly appreciate any inputs on the best statistcal approach to tackle this problem. I am thinking that we can find correlation coefficients between A and C, and between B and C, but I am not sure this answers the question. Also we do not know whether the correlation between them is linear or non linear. Thanks Lalitha

Hi all, I'm a newbie wrt R but that's okay, since I don't do any programming in R. What I do need to do is to administrate the activites of an R programmer, so my questions will be related to adminning R as opposed to statistcal programming. I hope that's okay with y'all. :-) I've been through most of the docs that I could find (the PDFs, StatsRUs, etc.) and I've found the answers to most of my questions, but not to an important one: how do I move a function from one namespace to another. On the chance t...

Dear all, Some functions like 'ROC(Epi)' can be used to perform ROC analyssi, but it needs us to specify the fitting model in the argument. Now i have got the predicted p-values (0,1) for the 0/1 response variable using some other approach, see the following example dataset: id mark predict.pvalue 1 1 0.927 2 0 0.928 3 1 0.928 ..................

I have been using R for a few months to plot my data, and fit statistical models and so on. It is stated that R is not only a package for statistcs and graphics but also a programming language. Currently I am working with Fortran 90 to do numerical simulations (1D reactive -transport), and subsequently visualize it in some external software (spreadsheet). As I now started using R I will plot my

Dears friends, I have been translating and extended, with educational porposes only, the available material in the www (http://zoonek2.free.fr/UNIX/48_R/all.html) "Statistcs avec R" for the Portuguese of Brazil. I consider the material very good and would like to share this work with anothers users R. Already I translated and I extended two chapters: Introduction to the R and analysis

Hi all, I skimmed through the archives and couldnt really find an answer to my question. One thing i dont understand of the description of the function boot() is the second variable for statistics. I have a sample of say 19 subjects out of these, using boot(), i would like to generate say 1000 samples. For these 1000 samples ill calculate an nlme() and ill use these 1000 estimators of a variable

Dear R developers, sorry about the empty bug-report that I seem to have filed earlier. (I wrote it via `bug.report()' from within R using `emacsclient'. I wasn't aware that I have to save the file after pressing C-x # and before sending it.) Hopefully this time it will work...... I noticed the following problem with the on-line help system: 1) I start an R session and type