Table 2.

Means, standard deviations, and repeated measures ANOVA results for younger siblings’ academic adjustment by dyad type and race.

	Dyad Type				Between Groups Analyses1			Repeated Measures Analyses2
	Same-sex		Mixed-sex		Dyad (D)	Race (R)	D × R	Time (T)	T × D	T × R	T × D × R
Adjustment	M	SD	M	SD
Importance of School for Future					F(1, 247)
African-American
7th grade	4.17	.64	3.99	.59	1.98	3.77* (.22)	.24	14.18*** .18 (−.32)		.34	3.89+
8th grade	3.89	.79	3.95	.66
European-American
7th grade	4.00	.60	3.95	.52
8th grade	3.86	.60	3.66	.72
Academic Self-Concept					F(1, 242)
African-American
7th grade	5.54	1.17	5.30	1.07	4.39* (.24)	.20	.01	10.97** (−.23)	.16	.05	.01
8th grade	5.32	1.19	5.04	1.10
European-American
7th grade	5.50	1.19	5.26	1.02
8th grade	5.27	1.19	4.95	1.31
GPA					F(1, 219)
African-American
7th grade	3.01	.59	3.01	.71	.03	21.69*** (−.56)	.80	.52	.00	.01	3.21+
8th grade	2.91	.62	3.06	.54
European-American
7th grade	3.32	.48	3.34	.45
8th grade	3.36	.55	3.24	.55

Note. F ratios are Wilks’ Lambda approximations.

¹Effect sizes,, calculated as ^d (see Howell, 2008), reported in parentheses under significant F statistics.

²Effect sizes represent gain in terms of SD at baseline (see Howell, 2008, p. 354).

^***p < .001,

^**p < .01,

^*p ≤ .05,

⁺p < .10.