TABLE 3.

Univariate model comparisons (log-likelihood fit statistics)

Model	Parameters	Persistence	Approach	Reactivity	General cognitive ability
Basic models
1. Full model	15	12,660	12,296	12,120	12,056
2. Drop β	14	12,666*	12,313**	12,179**	12,167**
3. Drop C	12	12,663	12,298	12,123	12,074*
4. Drop A	12	12,673**	12,329**	12,145**	12,108**
Sex differences
1. Full model	30	9704	9480	9287	8935
2. Equate trajectories	17	9722**	9494**	9290	8947**
3. Equate biometrics	21	9711	9491	9294	8938
4. Equate all	15	9736**	9509*	9301	8956
SES differences
1. Full model	30	12,630	12,258	12,078	11,986
2. Equate trajectories	17	12,638*	12,258	12,080	12,022**
3. Equate biometrics	21	12,635	12,271	12,082	11,922
4. Equate all	15	12,647	12,283*	12,106*	12,043**

^*Model fit is significantly different from model 1 at p < .05.;

^**Model fit is significantly different from model 1 at p < .01.