Effective in Wave 15 and continuing through the end of the survey, SIPP made a couple of important changes to our data collection process that data users should be aware of:
 
(1) All interviews were conducted via telephone.  In response to continuing budget pressure, we instructed the field representatives to conduct remaining Wave 15 and Wave 16 interviews only by telephone, with no personal visit component.
 
(2) All households that had been Type-As (household refusals) for two or more consecutive prior waves were dropped from the sample.  After Wave 1, we attempt to recontact all household members who were interviewed in Wave 1.  Recontact attempts continued to be made in subsequent waves regardless of number of prior waves missed or refused.  Starting in Wave 15, we eliminated continued recontact and conversion attempts for respondents who had refused for two or more consecutive waves.  Interviewing efforts were concentrated on locating and interviewing the people who had at least provided interviews in Waves 13 or 14.  Similarly, for Wave 16, we only attempted to interview those people who had provided interviews in Waves 14 or 15.