Survival Kit, software
This resource is to describe the usage of Survival Kit software package used for survival analysis (the paper). The focus will be on step by step description how to run the basic examples with fixed effects. The real advantage of the Survival Kit is its ability to handle very large databases (up to several million records) including random effects. This is however outside of scope of this beginner guide, while novice users should get familiar with the basic principles first.
The description deals with Survival Kit v6.06 available online at boku.ac.at.
General description of the Survival Kit
The Survival Kit is intended for survival analysis using proportional hazards model with a single response time. These models describe the hazard function of each individual (i.e. its limiting probability of dying at time t, given it is still alive just prior to t) as the product of a baseline hazard function and a positive (exponential) function of explanatory covariates. The baseline hazard function can be parametric (Weibull model) or left unspecified (Cox model).
When the failure time variable is discrete (i.e. has very few values) and many observations with the same failure times, many ties occur between failure times. In such case, the Cox model is not valid any more, but the "grouped data" approach should be used.
The Survival Kit consists from 3 main programs:
- Prepare - for database preparation, internal recoding
- Cox - for non parametric Cox model
- Weibull - for grouped data or parametric Weibull models
The reader should be familiar with the basic concepts of survival analysis. Basic knowledge of computer usage is expected.
- Survival analysis (StatSoft textbook)
- Introduction to Survival Analysis
- Data simulation (blogpost)
- Kaplan-Meier survival estimates (blogpost)
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- Sölkner J., Ducrocq, V., (1999) Workshop on Genetic Improvement of Functional Traits in Cattle - Longevity, Jouy-en-Josas, France
- Ducrocq, V., Sölkner, J. and Mészáros G. (2010). Survival Kit v6 – a Software Package for Survival Analysis. In: 9th World Cong. Genet. Appl. Livest. Prod., Leipzig, Germany.
- Cox, D.R. (1972) J. R. Stat. Soc., Series B, 34: 187-220.
- Prentice, R. and Gloeckler, L. (1978) Biometrics, 34:57-67.