search for: isotonic

...ed by an enquiry that I received in respect of a CRAN package "Iso" that I wrote and maintain. The question is this: Given observations y_1, ..., y_n, what is the solution to the problem: minimise \sum_{i=1}^n (y_i - y_i^*)^2 with respect to y_1^*, ..., y_n^* subject to the "isotonic" constraint y_1^* <= y_2^* <= ... <= y_n^* and the *additional8 bound constraint a <= y_1^* and y_n^* <= b, where a and b are given constants? I have googled around a bit (unsuccessfully) and have asked this question on crossvalidated a couple of days ago, with no response wha...

Hi, Has anyone written code for isotonic regression on ordered rectangular grids? Nathan Nathan Leon Pace, MD, MStat University of Utah Salt Lake City, UT 84132 Office: 801.581.6393 Fax: 801.581.4367 Cell: 801.558.3987 Pager: 801.291.9019 Home: 801.467.2925 [[alternative text/enriched version deleted]]

...rnative hypothesis on a set of groups (e.g., mu_a <= mu_b <= mu_c). There has been some literature on this topic -- a lot of this goes back to Bartholomew (1961); Gaines and Rice (see refs below) are the ones who've popularized it in the ecology community. The topic is closely related to isotonic regression, but all of the isotonic-regression stuff we've been able to discover in R so far (isoreg, the Iso and cir packages, etc.) are geared towards estimating smooth (or non-smooth) monotone relationships rather than towards testing ordered hypotheses. Computing p-values based on the Gaine...

Dear R-users Do you know of an easy way in R of performing "isotonic (unimodal)" regression ala BBBB, Barlow, Bartolomew, Brenner and Brunk. best regards Helgi -- Helgi Tomasson FAX: 354-552-6806 University of Iceland PHONE:354-525-4571 Faculty of Economics and Business Administration...

Hi All, I need some help with the package 'isotone'? I have a big matrix (long) and I want to apply 'lsSolver' possibly with 'activeSet' to each row of the matrix. The plan is to use function 'apply', I tried several ways, but didn't work. Not sure if the FUN is activeSet or lsSolver. If I use the loop, then it works, but very slow. for (i in 1:N) {

Before re-inventing the wheel I would like to ask: does anyone know about an optimizer in R which can reliably identify which value of X (Xopt) leads to Y (Yopt) closest to Ytarget in Y <- MonotoneStepFun(X) optionally with the restriction that Yopt <= Ytarget (at least if any Y <= Ytarget, otherwise any Yopt > Ytarget would be the preferred answer) If none is known, I will write

Dear Sir/Madam: this is shuangge Ma, graduate student in UW-Madison statistics department. I have a computational question. I have a function f(x,y). I want to find the y(x) that maximize f(x,y) under the constraint y(x) is a non-decreasing step function. Is there any R package or algorithm I can use for this purpose? thanks a lot for your time and help, Sincerely, Shuangge Ma

Dear All, A method for the estimation is univariate unimodal densities (with unknown mode) is described in "Statistical Inference under Order Restrictions" by Barlow et al.. Would anyone know whether there is an R-implementation (preferably with reference) for the estimation of univariate discrete unimodal densities (with unknown mode)? Thanks in advance for your help. Kind

Hi all, I'm looking for smooth monotone estimation packages, preferably using splines. I downloaded the 'cobs' package and intend to use it, but since it offers only quadratic splines based on L1 minimization, I'd like to compare its performance to that of a more 'mainstream' cubic-spline, L2-norm minimizing spline. Preferably a smoothing spline. Does anyone know of such

Hi, I'm trying to find an implementation of monotonic regression in R and I haven't been able to find anything that's really related to this. isoMDS in the MASS package uses monotonic regression, however, I was wondering if there is any standalone function for monotonic regression? Basically what I'm trying to do is implement monotonic regression where I can see not just the

This seems to be a recurrent topic, but I don't remember hearing a definitive answer. I also apologies for cross-posting. Say I have a numerical response variable and a bunch of multi-level factors I want to use for modeling. I don't expect factor interaction to be important so there will be no interactions in the model. All this would be a perfect job for ANOVA except for one additional

The homals package http://www.jstatsoft.org/v31/i04 will get a major programming overhaul. This will take some time, but what's a few years on a 40-year project. Suggestions from the audience are welcome. homals() has a core loop over the m variables in which 1. tapply is used to compute category quantification (centroids) 2. category quantifications are then adjusted to satisfy the

...- splines: spline regression function library - bootstrap: bootstrap utilities - integrate: numerical integration functions - date: date handling utilities - ctest: miscellaneous standard statistical tests - local: miscellaneous functions including isotonic regression I haven't gotten R-0.50a to compile under NEXTSTEP, but will try to make a newer version available eventually. --- Stephen Shiboski email: steve at biostat.ucsf.edu Division of Biostatistics voice: 415-476-0533 University of California San F...

...l functions fda::monfn Evaluates a monotone function fda::smooth.monotone Monotone Smoothing of Data mgcv::mono.con Monotonicity constraints for a cubic regression spline splines::backSpline Monotone Inverse Spline stats::isoreg Isotonic / Monotone Regression but none of these are specifically for an I-spline. Any help would be much appreciated. Helen Powell (Glsagow)

The homals package http://www.jstatsoft.org/v31/i04 will get a major programming overhaul. This will take some time, but what's a few years on a 40-year project. Suggestions from the audience are welcome. homals() has a core loop over the m variables in which 1. tapply is used to compute category quantification (centroids) 2. category quantifications are then adjusted to satisfy the

I think that users quite often want to answers to questions like ``Is there something to do FOO in R?'', where FOO might e.g. be ``isotonic regression''. The answer should be something like ``you can use BAR in package BAZ, or ...''. For this, full text search is not the right approach and the keywords are not enough. We could maybe search dedicated fields (like \title), but I think what we really want is something l...

Hi there, This is not a strictly related R question; I apologize for this. I'm interest in simulate the sampling distribution of the LRT, testing for trend among the levels of some categorical variable X in a regression model. (in practice this is achieved by assigning scores to the levels of X and fitting such numeric variable). To simulate the sampling distribution the steps are: 1.

Is there some reason why > (1:2)+(1:3) [1] 2 4 4 Warning message: In (1:2) + (1:3) : longer object length is not a multiple of shorter object length can't be made into an error? I realise it was there in S-PLUS, but since it produces a warning there can't be many examples on CRAN or Bioconductor using it, and I can't think of any situation where it would be used deliberately.

Hello, I am trying to call a FORTRAN subroutine from R. The Fortran code is @: http://lib.stat.cmu.edu/apstat/206 It performs a bivariate isotonic regression on a rectangular grid (m X n) matrix. I used the g77 compiler and successfully created a dll file and it also loads successfully from R. But somehow the programs fails to run properly. (I do get the correct result when I compile the FORTRAN code). Please see below and note that since my...

A colleague was asking me if R does multi-level modelling as opposed to multiple regression. Since I have no knowledge of multi-level modelling (except 5 minutes googling ) I thought that I would as here. Does are offer any multi-level modeling packages? It looked like arm might be one but I was not sure. Thanks