Table 1.

Data collection and sample size in analysis

	Fall 2002	Spring 2003	Spring 2004	Spring 2005	Spring 2006
3-year-old cohort	Baseline, Head Start (n = 2,119)	Head Start (n = 2,111)	4-year old, Head Start (n = 2,005)	Kindergarten (n = 1,907)	First grade (n = 1,867)
4-year-old cohort	Baseline, Head Start (n = 1,671)	Head Start (n = 1,667)	Kindergarten (n = 1,505)	First grade (n = 1,502)	No data collected
Full analysis sample	3,790	3,778	3,510	3,409	1,867

Notes: the number of observations presented in table was based on non-missing data of child care arrangements in spring 2003 and outcome variables by year and by cohort.