st: probable error, "weights invalid" using stset

["Brown, Elizabeth" <ebrown@prgs.edu>]

Dear all, 
I encountered a PROBABLE ERROR using stset that I'm unsure how to investigate/resolve. After stset, I get the following output, with a probable error with respect to 219 "weights invalid". What would cause weights to be invalid? How can I fix this? 

I'm using data from the Panel Study of Income Dynamics to examine multiple poverty transitions of families over the 1968 - 2007 period.  

With respect to how the weights were prepared, I first: 1) replaced any missing family weight values with family_weight[_n-1], and 2) made weights consistent within id by replacing  family weight with the last observed family weight value. In previous attempts to stset the data using weights, stata complained when weights were inconsistent within id. 

My stset  syntax + output is as follows:

stset t1 [pweight= lastweight], failure(end3==1) origin(enter==1) id(id) exit(exit==1 time .) enter(begin==1) 

                id:  id
     failure event:  end3 == 1
obs. time interval:  (t1[_n-1], t1]
enter on or after:  begin==1
exit on or before:  exit==1 time .
    t for analysis:  (time-origin)
            origin:  enter==1
            weight:  [pweight=lastweight]

------------------------------------------------------------------------------
  2052960  total obs.
   744905  ignored because never entered
   830804  obs. end on or before enter()
   285525  obs. begin on or after exit
      219  weights invalid                                      PROBABLE ERROR
------------------------------------------------------------------------------
   191507  obs. remaining, representing
    16923  subjects
    30084  failures in multiple failure-per-subject data
   208082  total analysis time at risk, at risk from t =         0
                             earliest observed entry t =         0
                                  last observed exit t =        39

Thank you! 

Liz 


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