survival analysis

  1. R

    How to find importance of an independant variable on a binary variable

    I am trying to learn statistics to help with my understanding of data I am getting in for the business I work for. I have a variable on whether someone left or are still customers. I have this listed as 0 or 1. I have a variable that is the variance of the customers last 8 months. I see...
  2. D

    SPSS Survival analysis - Should I split data file by groups or use covariates instead

    Hello! I have to assess different factors affecting the survival after transplantation. Can you advise me which is better (or more correct)? - to split the data file by groups (for example type of disease - malignant or non-malignant) and analyze the effect of other factor/s (e.g. HLA...
  3. J

    Surival analysis STATA - splitting up the time analysis interval/sum stats

    I am analyzing a data set - analysis of newspaper failure- over a 55 year time span and also looking at a time span of the last ten years. My goal is to analyze the two periods (split, but not in the conventional sense, the observation period) and to also get descriptive statistics on variables...
  4. D

    COX models and continuous variables

    Hello everyone. I have a simple and basic question about cox model. When I introduce a continuous variable in the model, the hazard ratio assessed for this variable relates the increase (decrease) of the risk after an increase of one unit of the continuous variable. How to extrapolate for more...
  5. M

    Cox PH regression on fixed-interval (1, 2, 5-year) survival

    Dear all, I am co-author on a manuscript on a study which follows a group of patients from a certain diagnosis and studies risk factors for survival. The main author has chosen to analyze fixed-interval survival rates (1, 2 and 5-year survival) and to compare the rates between two groups of...
  6. L

    Comparing survival against standard population

    Hello. I have the survival data (survival time + time of death) of a population after a certain treatment, as well as a standard population built from year-, age- and sex-specific mortality rates in the general population. The Kaplan-Meier curve for the treatment-population falls sharply...
  7. J

    How do I calculate time dependent covariates in SPSS?

    I am new to survival analysis and would appreciate some help! (I'm from psychology, and my discipline does not tend to conduct survival analysis) At the moment, I am having difficulty calculating time dependent variables in cox regressions. Intro to my data: 7 waves of data V1: event...
  8. I

    SPSS and multivariate analysis

    Dear Friends, I needed a help in deciding the right test using SPSS and how to do it please. I am comparing survival of two different cancers. Rt side colon vs left colon cancers. I have several variables for eg: 1) patients who had chemotherapy-yes/no 2) what stage at...
  9. A

    Modelling this non-linear relationship- please help

    Hi All, I'm using usual Cox regression where my outcome is time to a binary event. My variable of interest (a biological marker) appears to show a non-linear relationship with the outcome. I categorised it as 10 quantiles with the 6th as the reference category. The HR (with 95% CI) for...
  10. O

    outliers in survival probability

    Hi all, We use survival data of 90 patients that were divided in two sub groups. (31, 59). Two patients (out of the 31 sub group) survived 50% longer than all others. Are they considered outliers? What are the criterions to define outliers? Thanks for your help, Or :D
  11. P

    number of variables for a model

    I am now trying to build a cox model: h(t, beta) = h0(t)exp(X*beta) I have selected some variables from the data, and for a category variable, if it contains N categories, I will set up N-1 dummy variables for it, if so, there are 26 variables in my model, is it too many for a model? But...
  12. P

    cox model with time dependent covariate

    I am trying to fit a cox model: h(t, beta) = h0(t)exp(X*beta), while X = (x1, x2, ..., xN) but, for instance, x1 is binary with value of 0 or 1, but the hazard ratio of 1 and 0 is not proportional: t: 1 2 3 4 5 6 7 .... hazard ratio: 0.2 0.3...
  13. P

    Data input for coxph(Surv analysis

    Dear friends, I would like to ask this quite easy question regarding the data format for a coxph frailty model.
  14. R

    Survival analysis advice

    Hi, I'm having trouble wrapping my head around whether my data is censored or not, and interpreting the results of the (possibly inappropriate) model which I have selected to perform a regression. I have data recording incubation survival rates for 4 different penguin colonies, in two...
  15. O

    Survival Analysis Issue

    I am using stata to do survival analysis. I am interested in estimating poverty persistence. panel data: time id poverty 2001 1 0 2002 1 1 2003 1 1 2004 1...
  16. L

    How to interpret and compare models in Cox regression?

    Hallo, I am trying to interpret the results of a Cox regression; I am doing a PhD in medicine. I love statistics but my question is still pretty basic, I think, and I did not find an answer in previous threads. I have to compare different models (just a couple of predictors in each...
  17. R

    How to estimate count data models with observations with incomplete spell periods?

    Dear friends, I have a data base of 51 contracts. My research consists of estimating the determinants of recurrent contract renegotiations. Thus I built a cross section database and estimated a Poisson model, in which the dependent variable is the number of renegotiations. A reviewer argued...
  18. T

    Survival analysis: how do i include a random effect and interval censoring?

    Hi, I'm trying to use some form of survival analysis (e.g. accelerated failure time or proportional hazards) to study seed germination time. My data is interval censored (also called "grouped-time") and has a random effect (also called "frailty"). How can I do this, ideally in SAS? My...
  19. T

    How to do survival analysis in SAS with interval censoring and random effects

    Hi, I am interested in using survival analysis methods on seed germination data. I have just started reading Allison's Survival analysis in SAS. Accelerated failure time analysis (using PROC LIFEREG) and Cox proportional hazards models using PROC PHREG seem promising, but I have a feeling...
  20. B

    Relationship between sample mean and sample survival probability

    I am not sure if this question is very naive, but I was wondering if there is a relationship between sample mean and sample survival probability. For an exponential distribution with mean mu, S(t)=1-exp(-t/mu}) Now if I generate data from an exponential distribution, can the sample mean...