Table 3.

Summary of negative affect group demographic and self-report data

Variable	Low negative affect group (n = 175)		Medium negative affect group (n = 705)		High negative affect group (n = 170)		χ2/F	p value
	Mean	SD	Mean	SD	Mean	SD
Age	21.54	3.04	21.25	2.87	21.67	3.16	1.78	0.17
Percent female	57.70	N/A	52.60	N/A	56.50	N/A	1.93	0.38
Percent right handed	90.90	N/A	92.50	N/A	92.40	N/A	0.52	0.77
Years of education	14.84	1.86	14.63	1.93	14.84	2.11	1.35	0.26
Estimated IQ	112.74	8.97	113.19	9.29	113.78	8.89	0.57	0.57
Trait negative affect composite score	−1.15	0.27	−0.03	0.45	1.30	0.41	Selected	N/A
Percent family history of psychiatric illness	18.90	N/A	15.90	N/A	25.90	N/A	9.38	<0.01

N/A, Not applicable; selected indicates that the variable was used to define the groups and therefore, by design, differs between groups.