Many types of statistics will be produced by the Survey of Income and Program Participation (SIPP), but there is one type that was the driving force behind the unique design of the survey. To be fully successful, SIPP must tell us what happens to households over the course of time. From it we must obtain estimates of the patterns of income receipt, program participation, and labor force participation at the household and family level by a host of other characteristics. Of particular interest are parameters such as total annual household income and the number of families that have stopped drawing food stamps by demographic characteristics.