Table 3

Change in Weighting of Regression Estimates across Sibling and Switcher Samples (PSID)

	Number of Children in Family
	1	2	3	4	5+
Panel A: Share of Sample
All (no FFE)	0.123	0.273	0.238	0.147	0.134
Siblings sample (no FFE)	0.000	0.345	0.300	0.186	0.169
Switchers sample (FFE)	0.000	0.210	0.271	0.197	0.322
Panel B: Variance in Head Start
All (no FFE)	0.089	0.104	0.121	0.127	0.132
Siblings sample (no FFE)	0.000	0.024	0.050	0.059	0.068
Switchers sample (FFE)	0.000	0.045	0.098	0.131	0.174
Panel C: Regression Weights
All (no FFE)	0.171	0.257	0.284	0.117	0.101
Siblings sample (no FFE)	0.000	0.338	0.374	0.154	0.134
Switchers sample (FFE)	0.000	0.256	0.307	0.190	0.248

Source: Panel Study of Income Dynamics 1968–2011 waves.
Notes: This table shows the change in the composition of the PSID sample moving from all individuals and estimating a model without controls (“All (no FFE)”), to individuals that have at least one other sibling in the sample and estimating a model without controls (“Siblings Sample (no FFE)”), to individuals in families that have variation in Head Start attendance and estimating a model with family fixed effects (“Switchers sample (FFE)”). Panel A shows the share of individuals in each sample that come from a family with one child (zero siblings), two children, etc. Panel B shows the variance in Head Start for each family size and sample. For the switcher sample, this is calculated net of family fixed effects. Panel C shows the “regression weight” given to each family size in a given sample, denoted as ω_z and defined formally in Section III. The shares and regression weights do not sum to one for the “all sample” because this sample also includes an additional category of individuals who have an unknown number of siblings (due to a missing mother ID). These individuals account for 8.5 percent of the “all sample.”