question to stset _t and _t0

[Ying Ying Liu]

Hi guys, I am new to Stata, just wondering how stata calculates the value of _t and _t0.

Many thx

[Carlo Lazzaro]

Ying:
welcome to this forum.
I do hope that the following toy-example can give you some guidance:

. set obs 2
number of observations (_N) was 0, now 2

. g id=_n

. g time_in=2

. g time_out=4

. g failure=1 in 1
(1 missing value generated)

. replace failure=0 if failure==.
(1 real change made)

. g study_time= time_out- time_in

. stset study_time, failure(failure)

     failure event:  failure != 0 & failure < .
obs. time interval:  (0, study_time]
 exit on or before:  failure

------------------------------------------------------------------------------
          2  total observations
          0  exclusions
------------------------------------------------------------------------------
          2  observations remaining, representing
          1  failure in single-record/single-failure data
          4  total analysis time at risk and under observation
                                                at risk from t =         0
                                     earliest observed entry t =         0
                                          last observed exit t =         2

. list

     +--------------------------------------------------------------------+
     | id   time_in   time_out   failure   study_~e   _st   _d   _t   _t0 |
     |--------------------------------------------------------------------|
  1. |  1         2          4         1          2     1    1    2     0 |
  2. |  2         2          4         0          2     1    0    2     0 |
     +--------------------------------------------------------------------+

.

For more details, I would recommend you to get yourself familiar with the -st- entries in Stata .pds manual.
Last but absolutely not least, the valuable textbook https://www.stata.com/bookstore/surv...-introduction/ highly deserves to be included in the toolkit of Statalisters dealing with survival analysis.

[Ying Ying Liu]

So appreciated Carlo