Time to first event Cox
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stset End, failure(Failure==1) id(ID) origin(time Clinic) enter(time Clinic) scale(365.25) time0(Start)
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origin(time Clinic) and enter(time Clinic) specify that the individual first becomes at risk after the clinic date
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stcox varlist
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varlist represents a list of predictor variables in the model
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Andersen and Gill
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stset End, failure(Failure==1) id(ID) origin(time Clinic) enter(time Clinic) scale(365.25) time0(Start) exit(time.)
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scale(365.25) ensures that time is measured in years as opposed to days
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stcox varlist, efron robust
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efron specifies the use of the Efron method for analysing ties in the data
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Prentice, Williams and Peterson Total Time
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stset End, failure(Failure==1) id(ID) origin(time Clinic) enter(time Clinic) scale(365.25) time0(Start) exit(time.)
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time0(Start) specifies that 'Start' is the beginning of the time interval spanned by each record
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stcox varlist, efron robust strata(Risk_set)
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robust specifies that robust variance estimation is used to account for within-subject correlation of failure times
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exit(time.) ensures that an individual’s failures after the first are also recognised
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strata(Risk_set) ensures that a stratified cox model is fitted with a different underlying risk for each ordered failure event
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