Stratification

When stratification cells have changed and telephone numbers with Response Code 21 have to be reused, there are two options:

If the stratification was on input (data already available in the T-file before starting the interview), the previous response code may be used. No D-record was created, so no problem with duplicates arise.
If the stratification is on output (data that was collected in the questionnaire and *STRAT was used), respondents have already been contacted and told that they were not in your target group (and a D-record was created with that routing). If you initialize these numbers, the interview number has to be changed too.