. 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 6.

Cross-Trait Twin Correlations (Number of Pairs) for the Five Aspects of Mathematics

	MZ		DZ		DZss		DZos
Twin and measure	r	n	r	n	r	n	r	n
Twin 1 Underst–Twin 2 Applic	.56^*	297	.32^*	501	.24^*	263	.42^*	238
Twin 1 Comput–Twin 2 Applic	.47^*	301	.34^*	502	.35^*	264	.33^*	238
Twin 1 Interp–Twin 2 Applic	.54^*	297	.33^*	499	.31^*	262	.36^*	237
Twin 1 Non-Num–Twin 2 Applic	.53^*	302	.42^*	501	.36^*	263	.49^*	238
Twin 1 Comput–Twin 2 Underst	.45^*	294	.24^*	502	.26^*	267	.22^*	235
Twin 1 Interp–Twin 2 Underst	.54^*	292	.30^*	499	.35^*	265	.25^*	234
Twin 1 Non-Num–Twin 2 Underst	.55^*	296	.37^*	501	.36^*	266	.38^*	235
Twin 1 Interp–Twin 2 Comput	.48^*	298	.33^*	499	.30^*	263	.37^*	236
Twin 1 Non-Num–Twin 2 Comput	.58^*	303	.38^*	501	.35^*	264	.42^*	237
Twin 1 Non-Num–Twin 2 Interp	.51^*	297	.34^*	500	.29^*	263	.39^*	237

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 = DZ same-sex twins; DZos = DZ opposite-sex twins; underst = Understanding Number category; Applic = Mathematical Application category; Comput = Computation and Knowledge category; Interp = Mathematical Interpretation category; Non-Num = Non-Numerical Processes category.

p <.01.