Time Counts

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Time Counts
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Delay in politics and everyday life

• reopening of Laurel Park
• Iraqi elections

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Event history analysis...

• a roadmap for applied users
• ?the use of EHA
• ?key decisions and how to make them
• ?interpretation

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Why not OLS?

• the positive nature of duration data
• censoringDaschle v. McCain
• time-varying covariatesDaschle as party leader

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The basics of EHA

• the hazard ratethe rate at which units fail by t
  given that the unit had survived until t
• absolutely continuous v. discrete treatments
• given that Daschle has been in the Senate for 18
  years, what are the chances hell be defeated in
  2004?

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Parametric v. non-parametric models

• what is duration dependence?
• the s-curve in state innovation
• consider parametric models when
• ? theory for time dependency
• ? substantive interest in time dependency

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Some popular parametric models

• Weibull modelmonotonic baseline hazard
• non-monotonic modelslog-logistic and log-normal
• theory and data in choosing parametric models

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The Cox proportional hazards model

• duration dependency is left unspecified
• so what does this mean in practical terms?

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Time and rulemaking

• Cox Model
• Variable Est.(s.e.)
• Constant n.a.
• Adcomm -1.00(.25)
• Pages .0008(.004)
• Indep -.33(.29)
• p n.a.
• N 170
• Log-likel. -696.72

• Weibull Model
• Variable Est.(s.e.)
• Constant 5.89(.30)
• Adcomm .80(.25)
• Pages -.0007(.004)
• Indep .27(.30)
• p 1.23(.15)
• N 170
• Log-likel. -227.90

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Topics for another day

• interpreting for substantive meaning
• models for discrete duration data
• time-varying covariates
• repeated eventsmultiple and competing
• models for unobserved heterogeneity
• just scratching the surface

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If you want more

• ? Janet M. Box-Steffensmeier and Bradford S.
  Jones, Event History Modeling A Guide for Social
  Scientists
• ?Mario A. Cleves, William W. Gould, and Roberto
  G. Gutierrez, An Introduction to Survival
  Analysis Using Stata