​Authors evaluated the variation among and representativeness of controls identified using multiple methods for a population-based case-control study of breast cancer among Asian Americans, Native Hawaiians and Pacific Islanders (AANHPIs) in the San Francisco Bay Area using a unique combination of targeted recruitment strategies, including address-based sampling, community-based methods, and Internet-based and media-based approaches for recruiting controls, frequency matched on age and ethnicity to a population-based sample of cases.

Authors compared distribution of sociodemographic characteristics and cancer risk factors between recruitment sources. To ensure that the controls recruited were representative of the underlying at-risk population, the authors compared characteristics of the controls, by ethnicity and in aggregate, to data from the 2011–2012 California Health Interview Survey (CHIS), and adjusted the relative mix of recruitment strategies throughout the study as needed to achieve representativeness.​