similar to: Cox regression for prevalence estimates

Displaying 20 results from an estimated 1000 matches similar to: "Cox regression for prevalence estimates"

2003 May 01
3
Test statistic for Spearman correlation
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
2006 Sep 24
2
plotCI
Hi R masters! I need a Help with plot confidence intervals for one equation. I use library gplots and plotCI command in this script: require(gplots) ano <-1980:2002 rf<-exp(91.37162-0.04720281*ano) 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
2006 Dec 03
4
prop.trend.test issue
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
2004 Jan 09
2
Fit non-linear regressor
Hi R masters, Sorry for first mensage, this is orignal text... y<-c(2.8150,3.5239,4.0980,4.5845,5.0709,5.4824,5.8427,6.3214,6.7349,7.3651) x<-c(37,42,47,52,57,62,67,72,77,82) 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
2005 Mar 18
2
logistic model cross validation resolved
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
2004 Dec 15
3
(no subject)
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]]
2005 Aug 30
1
loglinear model selection
Hi R-masters! I have a problem and need your help. I have 9 discrete variables with 2 levels each. In exploratory analisys I generate one matrix with chi-square for tables with 2 ariables each with this script setwd("F:/") dados<-read.csv("log.csv")[,2:10] dados.x<-matrix(NA,ncol=9,nrow=9) for(i in 1:8){ for(j in (i+1):9){ tab<-table(dados[,i],dados[,j])
2002 Nov 13
4
[Newbie] Is there any support for work with grouped frequencies?
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
2004 Dec 29
3
gls model and matrix operations
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,
2003 Nov 27
2
MASS fitdistr()
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") :
2004 Sep 07
2
noncommutative addition: NA+NaN != NaN+NA
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
2005 Sep 05
2
Fisher's method in discriminant analysis
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
2006 Mar 02
2
How can I use r-cran-lmtest?
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
2002 Jul 01
1
chi square residuals
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 ...
2004 Apr 24
2
Changing Gui preferences
I want to modify my Gui preferences to get rid of the MDI toolbar and status bar. [ Under Windows XP and R 1.8.1 and 1.9.0.] When I uncheck the boxes and click "apply" I am told to save the preferences and the changes will take effect when restarting R. I click "save" and a box comes up to ask me to save Rconsole (I'm not sure where this should be saved but I navigate
2005 Dec 06
3
Coefficient of association for 2x2 contingency tables
Hi, Found no measure of association or correlation for 2x2 contingency tables in fullrefman.pdf or google. Can someone point to a package that implements such calculations? Thanx. -- Alexandre Santos Aguiar - consultoria para pesquisa em sa??de - R Botucatu, 591 cj 81 tel 11-9320-2046 fax 11-5549-8760 www.spsconsultoria.com
2002 Jul 06
1
R: one-sample binomial test
try ?power.prop.test > -----Messaggio originale----- > Da: Tim Wilson [mailto:wilson at visi.com] > Inviato: sabato 6 luglio 2002 6.05 > A: R-help > Oggetto: [R] one-sample binomial test > > > Hi everyone, > > Here's how I solved a problem for my stats class. I'm pretty sure I > understand what's going on, but I wonder if there's a more >
2005 Nov 02
5
Distribution fitting problem
I am using the MASS library function fitdistr(x, dpois, list(lambda=2)) but I get Error in optim(start, mylogfn, x = x, hessian = TRUE, ...) : Function cannot be evaluated at initial parameters In addition: There were 50 or more warnings (use warnings() to see the first 50) and all the first 50 warnings say 1: non-integer x = 1.452222 etc Can anyone tell me what I am doing
2005 Mar 12
1
Database reorganization
Hi people, I need reorganization several databases. I would like to know if that is possible in R. My problem is like that: original data base: Age x1980 x1981 1 5 8 3 7 9 5 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
2004 Jan 14
1
NLS mensagem error...
Hi R-masters, I have a problem with nls() and my research data. Look this example: X2000<-c(1.205268,2.850695,5.100860,8.571610,15.324513,25.468599,39.623418,61.798856,91.470006,175.152509) age<-c(37,42,47,52,57,62,67,72,77,82) fit <- nls(X2000~R*exp(A*age),start=list(R=.1,A=.1)) Error mensage: Error in nls(X2000 ~ R * exp(A * age), start = list(R = 0.1, A = 0.1)) :