Figure 5.

A directed acyclic graph of the relationship between siblings’ preterm birth (gestational age <37 weeks) and their score on the Phonological Awareness Literacy Assessment-Kindergarten test with overlaid estimates. Subscripts i and j denote family and sibling, respectively, where j = 1 is the younger sibling and j = 2 is the older sibling. PTB_ij is a preterm birth indicator, PALSK_ij the test score, D_i is a gain-score, and U_i is an unobserved confounder. Greek letters denote effects, and θ and δ are estimated using gain-score regression.