NISMART–2 Study Descriptions

National Household Surveys of Adult Caretakers and Youth
The Household Surveys were conducted during 1999, using computerassisted telephone interviewing methodology to collect information on missing child episodes from both adults and youth in a national probability sample of households. A total of 16,111 interviews were completed with an adult primary caretaker, resulting in an 80-percent cooperation rate among eligible households with children, and a 61-percent response rate. The total number of children identified by adult caretakers in the Household Survey sample was 31,787; these data were weighted to reflect the Census-based U.S. population of children age 18 years and younger. Each primary caretaker who completed an interview was asked for permission to interview one randomly selected youth in the household between the ages of 10 and 18. Permission was granted to interview 60 percent of the selected youth, yielding 5,015 youth interviews and a 95-percent response rate among the youth for whom permission was granted. These youth data were weighted to reflect the Census-based U.S. population of children ages 10–18. All of the adult caretakers and sampled youth in the Household Surveys were screened with a set of 17 questions to determine their eligibility for an indepth followup interview designed to collect detailed information about each type of episode.

One obvious limitation of the Household Surveys is that they may have undercounted children who experienced episodes but were living in households without telephones or were not living in households during the study period, including street children and homeless families. Although these are not large populations in comparison to the overall child population, they may be at risk for episodes.

Law Enforcement Study
The Law Enforcement Study (LES) sample consisted of all law enforcement agencies serving a nationally representative sample of 400 counties, including the 400 county sheriff departments and 3,765 municipal law enforcement agencies. The selection of counties took into account the size of their child populations.

Data were collected in two phases. In the first phase, a mail survey was sent to all law enforcement agencies in the sample. This questionnaire asked whether the agency had any stereotypical kidnappings (definition) open for investigation during 1997. The response rate for the mail survey was 91 percent. Agencies that reported any stereotypical kidnapping cases were then contacted by telephone for an extensive followup interview with the key investigating officer in each case. Data collection was completed for 99 percent of the cases targeted for followup interviews. Incorporating both phases of the LES, the combined response rate for the study was 91 percent. LES case weights were developed to reflect the probability of the agency and case having been included in the sample and to adjust for nonresponse and refusals.

Juvenile Facilities Study
The Juvenile Facilities Study was developed to estimate the number of runaways from juvenile residential facilities. Respondents were facility staff in a nationally representative sample of 74 facilities, including juvenile detention centers, group homes, residential treatment centers, and runaway and homeless youth shelters. Telephone interviews were conducted to determine the number of children who ran away from each facility in 1997, and details were obtained for the five most recent runaway episodes. All of the selected facilities that were operational participated; the response rate for episode-level interviews was 93 percent. Runaways were assigned weights to reflect the probability of having included the facility and episode in the sample and to adjust for nonresponse.