National Incidence Studies of Missing, Abducted, Runaway, and Thrownaway Children (NISMART), 1999

Parts 1-2: A list-assisted RDD (Random Digit Dial) methodology was used to select a nationally representative sample of telephone households from the GENESYS Sampling System frame. Typically, a list-assisted RDD design is a one-stage random selection process resulting in equal probabilities of selection (EPSEM) design and no clustering, with each household treated as a Primary Sampling Unit (PSU). A detailed description of the sampling design is in HOUSEHOLD SURVEY METHODS TECHNICAL REPORT which is included in this data collection. Part 3: A stratified, two-stage sample design was applied. In the first stage, 30 Primary Sampling Units (PSUs) were sampled from a listing of the national universe of counties and groups of small, adjacent counties. The PSUs were selected with probability proportionate to the number of children (aged 0 to 17) according to the 1990 Census. Within the 30 PSUs, a total of 922 eligible facilities were identified. This frame was stratified by type of facility, and 75 facilities were sampled with probability proportionate to size (PPS), using weighted capacity as the measure of size. Parts 4-6: Nationally representative sample of 400 counties. Counties were selected with probabilities proportional to size.