Table 3.

Summary of Differential Item Function (DIF) analyses for each Nicotine Dependence (ND) symptom.

	Cigarette ONLY	Cigarette + Cigar ONLY		Cigar Only		Smokeless WITH/WITH OUT OTHER FORMS
	(n= 9305)	(n= 581)		(n= 538)		(n= 615)
Nicotine Dependence Symptom	Reference	a	b	a	b	a	b
Mult-symptom Domain 1: Tolerance
Use much more to get effect	R	0	0	0	−	0	−
Increase use by 50 percent	R	0	0	0	0	0	0
Mult-symptom Domain 2: Withdrawal
Withdrawal syndrome	R	0	0	0	0	0	0
Use tobacco to keep from having withdrawal	R	0	0	0	+	0	0
Mult-symptom Domain 3: Use After Temporary Abstinence
Often JUST AFTER getting up	R	+	0	0	+	0	0
JUST AFTER use was not permitted	R	0	0	0	+	−	+
Remaining symptoms
Used tobacco more than you intended	R	0	0	+	0	0	0
Want to/try to stop or cut down	R	0	0	+	+	+	+
Chain smoking/using	R	+	−	+	0	+	−
Wake at up night to use tobacco	R	0	0	+	0	0	+
Give up or cut down on activities	R	0	0	+	−	0	0
Use tobacco despite health problem	R	0	+	+	+	0	+
Use tobacco despite anxious or depressed	R	0	0	0	0	0	0

Note: The discrimination (a) and severity (b) parameters from each tobacco use group were compared to parameters from cigarette users as a reference (‘R’). Comparisons with no significant DIF have ‘0’ symbol. Comparisons where the parameter was higher in the focal group have a ‘+’ and comparisons where parameter was lower in the focal group have a ‘−‘ symbol.