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Benefits and Drawbacks of a Multistage Screening Effort for Surveying Rare Populations

*Heather M Morrison, NORC at the Univerity of Chicago 
Alicia M Frasier, NORC at the University of Chicago 
Stephen J Blumberg, NCHS 
Matthew D Bramlett, NCHS 

Keywords: Screening, Sampling, Autism, Adoption, Children's Health

Conducting scientifically rigorous surveys of rare populations can be cost-prohibitive because obtaining a sufficient sample of eligible respondents via probability sampling requires a significant screening effort. As a result, surveys of hard-to-find respondents are sometimes undertaken using convenience samples that minimize the screening effort but come at the cost of scientific rigor. Recent survey work undertaken through the State and Local Integrated Telephone Survey (SLAITS) mechanism of the National Center for Health Statistics, however, demonstrates it is possible to control screening costs while maintaining the statistical properties of a probability design. SLAITS’ multi-stage approach screens for rare populations via one or more parent survey: the National Survey of Children with Special Health Care Needs and the National Survey of Children’s Health – both conducted on behalf of the Maternal and Child Health Bureau. These national surveys use the National Immunization Survey sampling frame to screen approximately six million telephone lines for eligible households yearly, resulting in a rich sample of certain rare populations. Once identified, these targeted rare populations participate in the salient follow-up survey. We have successfully employed this screening methodology to identify and interview nationally representative samples of adoptive parents in the National Survey of Adoptive Parents and the National Survey of Adoptive Parents of Children with Special Health Care Needs and more recently for parents of children with autism, intellectual disability, or developmental delay for the Survey of Pathways to Diagnosis and Services. These surveys would not be feasible without this multi-stage screening mechanism. There are, however, several drawbacks to this approach. While observed cooperation rates are high for the salient survey, response rates must be calculated accounting for response at all survey stages including screening. We examine the benefits and drawbacks of interviewing rare populations using this methodology including assessing survey cost, response rates, and sampling alternatives.