The Mental Health Surveillance Study (MHSS) is a continuous effort by SAMHSA to track the rates of serious mental illness (SMI) in American adults.
In 2008, the study integrated data from clinical interviews and the National Survey on Drug Use and Health (NSDUH) to provide accurate estimates of SMI prevalence.
The research involved a large sample size, with over 46,000 NSDUH interviews conducted and additional structured clinical interviews performed with a smaller group to ensure data quality and effective management of respondents.