The importance of post-hoc approaches for overcoming non-response and attrition bias in population-sampled studies

Population-based health studies are critical resources for monitoring population health\ud and related factors such as substance use, but reliable inference can be compromised\ud in various ways. Non-response and attrition are major methodological problems which\ud reduce power and can hamper the generalizability of findings if individuals who\ud participate and who remain in a study differ systematically from those who do not. In\ud this issue of SPPE, McCabe et al. studied participants of the 2001-2002 National\ud Epidemiologic Survey on Alcohol and Related Conditions, comparing attrition in Wave\ud 2 across participants with different patterns of substance use at Wave 1. The\ud implications of differential follow-up and further possibilities for addressing selective\ud participation are discussed.