National Incidence Studies of Missing, Abducted, Runaway and Thrownaway Children (NISMART), [United States], 2011

Household Survey Addresses were obtained from the United States Postal Service (USPS) through the Delivery Sequence File (DSF) which lists all addresses that receive mail deliveries. Prior to sampling the address frame was sorted and a sample of 130,000 addresses from all 50 states and the District of Columbia was selected with equal probabilities. The address sample was fielded in five cohorts. The first four cohorts used small subsamples, totaling 15,000 addresses, to pretest different versions of the mailed screener, reminders, and invitations to improve response rates; the last cohort comprised the remaining 115,000 addresses and received the final version of these materials. Upon receiving completed screener questionnaires, eligible households were sent invitations to complete an online survey. Invited parents/caretakers who did not complete the online survey were interviewers called respondents to complete a computer-assisted telephone interview (CATI). Youth surveys for NISMART-3 were created and administered, similar to NISMART-2, but not used in analysis due to low case yield. Law Enforcement Survey The LES obtained a sample of stereotypical kidnapping cases through a survey of all law enforcement agencies (n=4,644) located in a nationally representative sample of 433 counties. Law enforcement agencies were located in the sampled counties using the 2011 National Directory of Law Enforcement Administers (www.safetysource.com), which provided a database listing all of the municipal and county law enforcement agencies and state criminal investigation agencies in the United States by address, county and other details. Agencies in the sample were sent a mail survey that asked whether the agency investigated any stereotypical kidnappings in their jurisdiction between October 1, 2010 and September 30, 2011. When agencies reported such investigations, telephone interviews were conducted with investigating officers to obtain details of the episodes.