Some populations pose special challenges for researchers because they are particularly difficult to sample, locate, or interview. Rare populations, such as children with special health care needs, racial and ethnic minorities, and men who have sex with men, are difficult to sample efficiently. Others like the homeless are absent from traditional sampling frames. Sampling such populations in a scientific but cost-effective way requires specialized techniques such as respondent-driven sampling, multi-frame approaches using targeted lists, stratified sampling with geographic oversamples, or rapid eligibility screening. Other populations may be hard to locate, access, or recruit due to barriers to entry, cultural differences, or dangerous settings. Examples include research conducted on Native American reservations, in homeless shelters, or with the incarcerated. These settings can present unique barriers to access and issues for recruitment that must be overcome before research can begin. Interviewing special populations and obtaining accurate survey measurements and responses can also pose unusual challenges. Language issues, cultural differences, illiteracy, and intellectual disability can present problems of question comprehension; questions about sensitive topics, stigmatized actions, or illegal behaviors can lead to mismeasurement if not composed and presented with care.

Since the 1940s, NORC has demonstrated expertise in sampling, locating, and working with special populations that require tailored and culturally-sensitive protocols and interactions. From research into Native American housing needs and rural U.S. veterans’ access to healthcare to measurement of teen dating violence and the economic hardship of Chicago’s urban poor; from studies of the health and social interactions of older Americans to the experience of sexual violence of former prisoners; from examining the social support network of men who have sex with men to evaluating methods of collecting data on immigration status, NORC has extensive experience conducting research on difficult and sensitive topics with rare and hard-to-reach populations.