Table 3 Effects of Being Old-for-Grade on Older Siblings’ Grades by Distance in Focal Child’s and Sibling’s Age

Age Difference	OLS	2SLS	2SLS	Observations
Math (SD)
1–3 years	0.107^***	0.122	0.056	31,505
1–3 years	(0.012)	(0.104)	(0.100)
4–6 years	−0.128^***	−0.032	−0.115	14,024
4–6 years	(0.019)	(0.183)	(0.174)
7–9 years	−0.132^***	1.065^**	0.985^**	4,557
7–9 years	(0.034)	(0.392)	(0.355)
Danish essay (SD)
1–3 years	−0.066^***	0.134	0.116	31,505
1–3 years	(0.012)	(0.104)	(0.098)
4–6 years	−0.079^***	0.096	0.003	14,024
4–6 years	(0.018)	(0.182)	(0.171)
7–9 years	−0.119^***	0.037	0.101	4,557
7–9 years	(0.033)	(0.345)	(0.311)
Danish grammar (SD)
1–3 years	−0.102^***	0.106	0.079	31,505
1–3 years	(0.012)	(0.103)	(0.099)
4–6 years	−0.121^***	0.279	0.189	14,024
4–6 years	(0.018)	(0.184)	(0.175)
7–9 years	−0.139^***	0.768^*	0.763^*	4,557
7–9 years	(0.033)	(0.368)	(0.336)
Danish oral (SD)
1–3 years	−0.081^***	0.097	0.076	31,505
1–3 years	(0.012)	(0.103)	(0.099)
4–6 years	−0.101^***	−0.043	−0.123	14,024
4–6 years	(0.019)	(0.182)	(0.174)
7–9 years	−0.105^**	−0.124	−0.070	4,557
7–9 years	(0.034)	(0.342)	(0.316)
Distance to cutoff	X	X	X
Covariates	X		X

↵Notes: Table shows the estimated effects of being old-for-grade based on OLS and 2SLS regressions of older siblings’ grades at the end of Grade 9. Each table cell represents an estimate for one specific subgroup defined by age distance between siblings. Cutoff dummy (January = 1) used as instrument. Conditioning set includes distance to cutoff, cohort fixed effects, and background characteristics (see Table 2). Standard errors in parentheses +p < 0.10, *p < 0.05, **p < 0.01, ***p < 0.001.