Table 2. SAOMs Predicting the Selection of study Partners (S) and the Perception of Popular Peers (P) as Well as Academic Self-Concepts (Behavior Dynamics).

	Model S.2		Model S.3		Model P.2		Model P.3
Measure	Est.	95% CI	Est.	95% CI	Est.	95% CI	Est.	95% CI
Note. Bold print = significant (p < .05). ASC = academic self-concept; BFLPE = Big-Fish-Little-Pond Effect; SES = socioeconomic status.
Network dynamics: Tie selection
Structural network effects (reciprocity. transitive triplets. transitive reciprocal triplets. outdegree: activity. outdegree:density. indegree: popularity)		x		x		x		x
Gender: ego	0.03	[−0.07, 0.12]	0.03	[−0.05, 0.11]	−0.03	[−0.08, 0.02]	−0.03	[−0.08, 0.01]
Gender: alter	0.05	[−0.04, 0.13]	0.05	[−0.05, 0.14]	−0.07	[−0.12, −0.03]	−0.08	[−0.13, −0.03]
Gender homophily (same gender)	0.68	[0.62, 0.75]	0.68	[0.59, 0.75]	0.34	[0.29, 0.39]	0.34	[0.29, 0.39]
SES homophily (similarity)	0.14	[−0.03, 0.3]	0.14	[−0.03, 0.33]	0.10	[−0.03, 0.22]	0.08	[−0.04, 0.22]
Ethnic homophily (same ethnic background)	0.19	[0.12, 0.26]	0.20	[0.14, 0.26]	0.06	[0.01, 0.11]	0.06	[0.01, 0.11]
Achievement ego	−0.06	[−0.1, −0.02]	−0.07	[−0.11, −0.02]	−0.04	[−0.07, −0.01]	−0.04	[−0.07, −0.01]
Achievement alter	0.08	[0.03, 0.12]	0.06	[0.02, 0.11]	0.01	[−0.02, 0.04]	0.01	[−0.02, 0.04]
Achievement similarity	0.46	[0.11, 0.78]	0.47	[0.12, 0.74]	0.17	[−0.08, 0.42]	0.16	[−0.06, 0.38]
ASC ego	0.08	[0.05, 0.12]	0.08	[0.05, 0.12]	0.02	[−0.01, 0.05]	0.02	[−0.01, 0.04]
ASC alter	0.01	[−0.02, 0.05]	0.02	[−0.02, 0.05]	0.02	[0, 0.05]	0.02	[0, 0.04]
ASC similarity	0.16	[−0.04, 0.33]	0.11	[−0.08, 0.29]	−0.01	[−0.14, 0.12]	−0.02	[−0.15, 0.12]
Behavior dynamics: Academic self-concept
Linear and quadratic shape effect		x		x		x		x
Main effects of gender. SES and ethnic origin		x		x		x		x
Individual achievement	0.25	[0.21, 0.29]	0.28	[0.24, 0.33]	0.27	[0.22, 0.32]	0.28	[0.24, 0.32]
Av. achievement of whole classroom (BFLPE)			−0.25	[−0.34, −0.15]			−0.16	[−0.27, −0.01]
Av. achievement of nominated peers:
Study partners	−0.05	[−0.12, 0.03]	0.11	[0.02, 0.2]
Popular peers					−0.16	[−0.24, −0.09]	−0.02	[−0.17, 0.09]