similar to: Using t tests

Hi, I'm reading van Belle et al "Biostatistics" and trying to run a cox test using a dataset from: http://faculty.washington.edu/~heagerty/Books/Biostatistics/chapter16.html (Primary Biliary Cirrhosis data link at top of the page), I'm using the following code: --------------- start of code library(survival) liver <-

Hello, I probably have a syntax error in trying to generate an expected survival curve from a weighted cox model, but I can't see it. I used the help sample code to generate a weighted model, with the addition of a "weights=albumin" argument (I only chose albumin because it had no missing values, not because of any real relevance). Below are my code with the resulting error

The data set in R is wrong. I've found mistakes on 2 lines in a quick look. I don't know if the data is incorrect in the Appendix of Fleming and Harrington as well (someone seems to have borrowed my copy), which is where the data set appears to have been taken from, given all the "-9" codes in it. (Note, Tom Fleming originally got the data from me, so I'm fairly

Hi: I have a few clarification questions about the elements returned by the coxph function used in conjuction with a frailty term. I create the following group variable: group <- NULL group[id<50] <- 1 group[id>=50 & id<100] <- 2 group[id>=100 & id<150] <- 3 group[id>=150 & id<200] <- 4 group[id>=200 & id<250] <- 5 group[id>=250

Dear list, I have been struggling with this for some time now, and for the last hour I have been struggling to make a working example for the list. I hope someone out there have some experience with plotting longitudinal data that they will share. My data is some patient data with three different time stamps. First the patients are identified at different times (first time stamp). Second, they

I have a dataset at a hospital level (as opposed to the patient level) that contains number of patients experiencing events (call this number y), and the number of patients eligible for such events (call this number n). I am trying to model logit(y/n) = XBeta. In SAS this can be done in PROC LOGISTIC or GENMOD with a model statement such as: model y/n = <predictors>;. Can this be done

I'm trying to fit a Cox proportional hazards model to some hospital admission data. About 25% of the patients have had at least one admission, and of these, 40% have had two admissions within the 12 month period of the study. Each patients has had one of 4 treatments, and one of the treatment groups has had no admissions for the period. I used:

Hi R users I have a dataset which represents points that are market by patients as the source of pain. Basically the patients indicates by a cross on a chest pictures where he/she thinks is the source of pain. The data was then digitalized by divinding the chest into small squares and each square was give value 1 if it was the center 2 if it was touched by the markings and 3 if it was not

Dear R-users! I am using R 1.7.0, under Windows XP. Having some hospital discharge data (admission date and discharge date for each patient), I want to get the number of patients in the hospital on a given date. My data look like (simple example): > x <- data.frame(patid=c("pat1", "pat2"), adm.date = c("15.03.2002", "16.03.2002"),

Dear R-forumites, I want to apply a Wilcoxon test on subsets of the data frame mydata, splitted using the myindice variable. When I send : wilcoxtest <- by(mydata, mydata$myindice, function(x) {wilcox_test(x$value~x$fact)}) I get : Error in eval(expr, envir, enclos) : object "x" not found whereas wilcoxtest <- by(mydata, mydata$myindice, function(x)

Dear All, I have two simple data samples (no groups or factors, etc.) and would just like to compute the two-sample Wilcoxon Rank Sum test using the wilcox_test function contained in the coin package, which is reportedly better than the regular wilcox.test function because it performs some adjustment for ties. Would anyone know how to craft a script to perform this task? Much appreciated. Janh

I am attempting to model data with the following variables: timepoint - n=48, monthly over 4 years hospital - n=3 opsn1 - no of outcomes total.patients skillmixpc - skill mix percentage nurse.hours.per.day Aims To determine if skillmix affects rate (i.e. no.of.outcomes/total.patients). To determine if nurse.hours.per.day affects rate. To determine if rates vary between

Hello! I would like to visualize the hospitalization within one year of several patients using a bar chart. For each patient the stay in a hospital should be illustrated with a dark colour a if there is a stay at home between 2 hopital stays, it should be illustrated with a bright colour. e.g. P1 |//////| |///| |////////| P2 |//////////| P3 |//|

Hi, I became a little bit confused when working with the Wilcoxon test in R. As far as I understood, there are mainly two versions: 1) wilcox.test{stats}, which is the default and an approximation, especially, when ties are involved 2) wilcox_test{coin}, which does calculate the distribution _exactly_ even, with ties. I have the following scenario: #---BeginCode--- # big example size = 60

Dear WizaRds, I am struggling with the use of twophase in package survey. My goal is to compute a simple example in two phase sampling: phase 1: I sample n1=1000 circuit boards and find 80 non functional phase 2: Given the n1=1000 sample I sample n2=100 and find 15 non functional. Let's say, phase 2 shows this result together with phase 1: ...................phase1........

Dear Sir, How do I change the intervals on the x axis of a histogram plot; let us say for example the intervals were 0,5,10,15,and 20, and I wanted to change the intervals to 0,2,4,6,8,10,12,14,16,18,20. I look forward to receiving your words of wisdom. Ivo [[alternative HTML version deleted]]

Hi there, Can anyone please help me because I am going to get crazy with the pbc data set. I just want to apply simple cox regression in the data set. I am a beginner in R but I don't think I am doing anything wrong. I have the book of Fleming and Harrington 1990. I perform cox regression by typing: out<- coxph(Surv(times/365,status)~log(bili)+log(proth)+edema+log(albumin)+age) out

I need a picture like this: http://rwiki.sciviews.org/doku.php?id=graph_gallery:graph38 http://rwiki.sciviews.org/doku.php?id=graph_gallery:graph38 but when I try compile it require("hexbin") data(NHANES)# pretty large data set! good <- !(is.na(NHANES$Albumin) | is.na(NHANES$Transferin)) NH.vars <- NHANES[good,

Hello, I have a general help question that some of you might be able able to help. I would like to design a study (a two group comparison) based on reduction on events(say hospital admissions). In a previous study hospital admission rate of 140 admissions per 72 patients (over a 4 month period) has been observed. That is rate is about 1.9. In order to see the admission rate reduction of 50% over

Does anyone know why wilcox.exact gives W-statistic 6 instead of 12 as indicated below. 12 is the rank sum of group 0 of x, which is the linear statistic computed by wilcox_test. y<-c(1,2,3,4,5) x<-c(1,1,0,0,0) (a) wilcox.exact wilcox.exact(y~x) Exact Wilcoxon rank sum test data: y by x W = 6, p-value = 0.2 alternative hypothesis: true mu is not equal to 0 (b) wilcox_test