2. METHODS
The retrospective analysis was based on 2008 data obtained from the National Sample Survey of Registered Nurses (NSSRN). Since 1977, the Health Resources and Services Administration (HRSA) has overseen the collection of NSSRN data every four years18. The NSSRN contains the central data repository workforce estimates for nurses in the United States, including household income, demographic characteristics, training, etc.19. The unit of analysis is the nurse.