Observations of Mother-Twin Interactions at 9 Months: User's Manual for the Early Childhood Longitudinal Study, Birth Cohort (ECLS-B) 9-month Twin Triad Restricted-Use Data File (NCES 2007-047)

This User's Manual for the Twin Triad Data File describes the design, instrumentation, coding methodology, and special issues pertaining to the twin triad data file from the Early Childhood Longitudinal Study, Birth Cohort base year (9-month) data collection. Also included is information to help users access and use the twin triad data file in conjunction with the main ECLS-B restricted-use data files.