. Author manuscript; available in PMC: 2013 Apr 1.

Published in final edited form as: Cognit Ther Res. 2012 Apr;36(2):156–164. doi: 10.1007/s10608-011-9425-4

Table 3.

Hierarchical multiple regression predicting symbol digit (N = 72)

Variable	B	SE B	β	R²	ΔR²
Step 1	–	–	–	.06	.06
Age	−.14	.19	−.08	–	–
Education	−.87	.62	−.16	–	–
Complaint duration	−.13	.09	−.16	–	–
Step 2	–	–	–	.15^*	.09^*
Age	−.09	.19	−.06	–	–
Education	−.65	.61	−.12	–	–
Complaint duration	−.14	.09	−.17	–	–
TWT mean	.06^**	.02^**	.41^**	–	–
TST mean	.03	.02	.23	–	–
Step 3	–	–	–	.15	.00
Age	−.08	.19	−.05	–	–
Education	−.62	.62	−.12	–	–
Complaint duration	−.14	.09	−.18	–	–
TWT mean	.07^*	.03^*	.45^*	–	–
TST mean	.03	.02	.24	–	–
TWT variability	−.01	.07	−.02	–	–
TST variability	−.02	.05	−.05	–	–

TWT Total Wake Time, TST Total Sleep Time

P < .05,

^**

P < .01