English, Article, Journal or magazine article edition: The influence of categorizing survival time on parameter estimates in a Cox model Anika Buchholz; Willi Sauerbrei; Patric Royston

User activity

Share to:
 
Bookmark: http://trove.nla.gov.au/version/176029
Physical Description
  • preprint
Language
  • English

Edition details

Title
  • The influence of categorizing survival time on parameter estimates in a Cox model
Author
  • Anika Buchholz
  • Willi Sauerbrei
  • Patric Royston
Physical Description
  • preprint
Notes
  • With longer follow-up times, the proportional hazards assumption is questionable in the Cox model. Cox suggested to include an interaction between a covariate and a function of time. To estimate such a function in Stata, a substantial enlargement of the data is required. This may cause severe computational problems. We will consider categorizing survival time, which raises issues as to the number of cutpoints, their position, the increased number of ties, and the loss of information, to handle this problem. Sauerbrei et al. (2007) proposed a new selection procedure to model potential time-varying effects. They investigate a large dataset (N =​ 2982) with 20 years follow-up, for which the Stata command stsplit creates about 2.2 million records. Categorizing the data in 6-month intervals gives 35,747 records. We will systematically investigate the influence of the length of categorization intervals and the four methods of handling ties in Stata. The results of our categorization approach are promising, showing a sensible way to handle time-varying effects even in simulation studies. References: Sauerbrei, W., Royston, P. and Look, M. (2007). A new proposal for multivariable modelling of time-varying effects in survival data based on fractional polynomial time-transformation. (Biometrical Journal, in press)
  • RePEc:boc:dsug07:03
Language
  • English
Contributed by
OAIster

Get this edition

Other links

  • Set up My libraries

    How do I set up "My libraries"?

    In order to set up a list of libraries that you have access to, you must first login or sign up. Then set up a personal list of libraries from your profile page by clicking on your user name at the top right of any screen.

  • All (1)
  • Unknown (1)
None of your libraries hold this item.
None of your libraries hold this item.
None of your libraries hold this item.
None of your libraries hold this item.
None of your libraries hold this item.
None of your libraries hold this item.
None of your libraries hold this item.
None of your libraries hold this item.

User activity


e.g. test cricket, Perth (WA), "Parkes, Henry"

Separate different tags with a comma. To include a comma in your tag, surround the tag with double quotes.

Be the first to add a tag for this edition

Be the first to add this to a list

Comments and reviews

What are comments? Add a comment

No user comments or reviews for this version

Add a comment