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Hello, I'm an MD working in an eye clinic. I'm learning by myself to use R for use in my research works and for implementation in a software project. There are some authors who recomends the use of Cox regression as a substitute for Logistic regression (<a href="http://www.biomedcentral.com/1471-2288/3/21.pdf"> Barros AJD, Hirakata VN. BMCMedical Research Methodology, 2003;

...) ciw.f<-sqrt(1.766073e-08) plotCI(ano,rf,uiw=ciw.f) But in the graph not shown the errors bar and I have this error msg zero-length arrow is of indeterminate angle and so skipped Well, where is my eror? Thanks in advance Bernardo Rangel Tura, MD, PhD National Institute of Cardiology Laranjeiras Rio de Janeiro Brazil

In the ouput below, what is the "S" statistic (S = 96) that is used for Spearman? I don't have easy access to the books cited on the help page. Other texts and web sources that I have found use t or z as a test for Spearman, perhaps inappropriately. Can anyone tell me how S is computed or refer to a web resource? I see from the code for that: q <- as.integer((n^3 - n) * (1

...NA Now I need fit a loglinear model with this variables, but I need know have a command with generate ALL models with the set this 8 vairables (ALL minus [,8]) incluindind the interactions. Can Anyone Help me? Thanks in advance Bernardo Rangel Tura, MD, MSc National Institute of Cardiology Laranjeiras Rio de Janeiro Brazil -- No virus found in this outgoing message. Checked by AVG Anti-Virus.

Dear R-helper, I would like to compare the AUC of two logistic regression models (same population). Is it possible with R ? Thank you Roman Rouzier [[alternative HTML version deleted]]

...2,57,62,67,72,77,82) I need fit R and A in y=f(x)=R*exp(A*x), with minimize sd= sqrt(SRR/(n-2)) where SRR is Sum of the Square of the Residuals and n is number of data points (in this case 10) How do I make this? Thanks in advance Bernardo Rangel Tura, MD, MSc National Institute of Cardiology Laranjeiras Rio de Janeiro Brazil

This post is NOT a question, but an answer. For readers please disregard all earlier posts by myself about this question. I'm posting for two reasons. First to say thanks, especially to Dimitris, for suggesting the use of errorest in the ipred library. Second, so that the solution to this problem is in the archives in case it gets asked again. If one wants to run a k-fold cross-validation

I have the clinical study data. Year 0 Year 3 Retinol (nmol/L) N Mean +-sd Mean +-sd Vitamin A group 73 1.89+-0.36 2.06+-0.53 Trace group 57 1.83+-0.31 1.78+-0.30 where N is the number of male for the clinical study. I want to test if the mean serum retinol has increased over 3 years among subjects in the vitamin A group. > 1.89+0.36

Hi, I have this table (BTW, published by FBI and representing age distribution of the WTC tragedy victims): "LABEL" "FREQ" "MIDPOINT" "1" "Infant (under 1)" 0 "2" "1 to 4" 5 "3" "5 to 8" 1 "4" "9 to 12" 3 "5" "13 to 16" 0 "6" "17 to

Dear R experts, I am trying to use the R MASS library fitdistr() to fit the following list: k21stsList<-c(0.76697,0.57642,0.75938,0.82616,0.93706,0.77377,0.58923,0.37157,0.60796,1.00070,0.97529,0.62858,0.63504,0.68697,0.61714,0.75227,1.16390,0.66702,0.83578) as follows, library(MASS) fitdistr(k21stsList, "normal") But, I get Error in fitdistr(k21stsList, "normal") :

...Error in nls(X2000 ~ R * exp(A * age), start = list(R = 0.1, A = 0.1)) : singular gradient In addition: Warning message: no finite arguments to min; returning Inf How I fix this problem? Other command? Thanks in advance Bernardo Rangel Tura, MD, MSc National Institute of Cardiology Laranjeiras Rio de Janeiro Brazil

...ts (in >different windows) ? Hi I think wich the correct code is: >for(i in 1:L) { >windows() > plot(listOfFunctions[[i]]) >} This work in my computer. I dont know thje answer for your second question Best wishes Bernardo Rangel Tura, MD, MSc National Institute of Cardiology Laranjeiras Rio de Janeiro Brazil

...t) = base mortality on year t b(x,t) = exponential rate of mortality for age x on year t b(t) = exponential rate of mortality on year t I wish is possible fit this system in R? Case positive Which the best method? Thanks in advance Bernardo Rangel Tura, MD, MSc National Institute of Cardiology Laranjeiras Rio de Janeiro Brazil

Hi guys. Check this out: > NaN +NA [1] NaN > NA + NaN [1] NA I thought "+" was commutative by definition. What's going on? > R.version _ platform powerpc-apple-darwin6.8 arch powerpc os darwin6.8 system powerpc, darwin6.8 status major 1 minor 9.0 year 2004 month 04 day 12 language R > (Both give NA under linux, so it looks

...9 15 7 11 20 future data base year age x 1980 1 5 1980 3 7 1980 5 9 1980 7 11 1981 1 8 1981 3 9 1981 5 15 1981 7 20 Thanks in advance Bernardo Rangel Tura, MD, MSc National Institute of Cardiology Laranjeiras Rio de Janeiro Brazil -- No virus found in this outgoing message. Checked by AVG Anti-Virus.

...08 7 138 8 1.1902613 8 115 9 0.9619330 9 92 10 0.7037427 10 69 11 0.8591257 11 46 12 1.2215657 12 23 Well I need help for solution this problem.... Somebody can help me? Thanks in advance Bernardo Rangel Tura, MD, MSc National Institute of Cardiology Laranjeiras Rio de Janeiro Brazil -------------- next part -------------- No virus found in this outgoing message. Checked by AVG Anti-Virus.

Hi, I'm using mda library to solve a discriminant analysis. I get results, but the thing is that I want to use Fisher's method to obtain the classification functions and I'm lost in what I should do: libraries to use, ... Can anybody give me a clue?? Thanks. Carlos Niharra L??pez

Hi, I installed the package r-cran-lmtest in a Debian Sid but I can't use it. I typed "lmtest" but nothing occur. Any help? Thanks. -- S?vio Martins Ramos - Arquiteto Rio de Janeiro ICQ 174972645 Pirataria n?o! Seja livre: Linux http://www.debian.org

Dear List: I am estimating a gls model and am having to make some rather unconventional modifications to handle a particular problem I have identified. My aim is to fit a GLS with an AR1 structure, obtain the variance-covariance matrix (V), modify it as needed given my research problem, and then reestimate the GLS by brute force using matrix operations. All seems to be working almost perfectly,

dear list, I'm a newbie with R but it seems very interesting to me. First, to train myself and students, I'd like to use it for teaching labs next year. one of my labs deals with the barn owl predation in my region. tudents have to work on a contingency table tytogrp : station1 station2 station3 ... n1,1 n1,2 n1,3 ... n2,1 n2,2 n2,3 ...