. Author manuscript; available in PMC: 2009 Sep 14.

Published in final edited form as: J Educ Psychol. 2007 Feb 1;99(1):128–139. doi: 10.1037/0022-0663.99.1.128

Table 2.

Intraclass Correlations (Number of Pairs) for the Five Aspects of Mathematics

	MZ		DZ		DZss		DZos
Measure	ICC	n	ICC	n	ICC	n	ICC	n
Applic	.63^*	300	.46^*	500	.42^*	263	.49^*	237
Underst	.60^*	299	.37^*	502	.33^*	265	.41^*	237
Comput	.55^*	301	.32^*	502	.31^*	265	.32^*	237
Interp	.51^*	294	.29^*	498	.27^*	262	.31^*	236
Non-Num	.59^*	292	.35^*	501	.34^*	266	.38^*	235

Note. The numbers are after the exclusion of all pairs in which at least one twin was an outlier or had missing data. MZ = monozygotic; DZ = dizygotic; DZss = same-sex twins; DZos = opposite-sex twins; ICC = intraclass correlation; Applic = Mathematical Application category; Underst = Understanding Number category; Comput = Computation and knowledge category; Interp = Mathematical Interpretation category; Non-Num = Non-Numerical Processes category.

p < .01.