Table 1.

Summary Statistics of the Aggregated 90 Day Assessment Period for the First and Second TLFB Measurement Occasions

	First Assessment					Second Assessment
Item	Mean	Median	SD	Max	n	Mean	Median	SD	Max	n
Maximum drinks	12.0	9.0	13.3	80	70	11.2	8.0	11.2	70	70
Drinking days	16.1	7.0	22.1	88	68	16.3	8.0	21.6	89	69
Heavy drinking daysa	13.4	6.0	20.0	88	49	11.5	5.0	16.5	89	48
Total drinks	152.8	37.0	521.3	4251	68	147.9	38.0	524.5	4331	69
Marijuana use days	23.8	9.0	30.5	90	44	26.2	11.0	30.8	90	42
Cocaine use days	14.8	5.5	22.1	81	14	13.1	4.0	16.4	46	15
Amphetamine use days	14.0	14.0	0.0	14	1	7.0	7.0	0.0	7	1
OTC stimulant days	24.7	12.0	31.0	60	3	20.3	1.0	33.5	59	3
Sedative use days	27.9	21.0	28.3	81	8	29.3	18.0	30.5	87	7
Opiate use days	29.3	11.5	40.7	90	4	21.6	14.5	29.2	90	8
Hallucinogen use days	1.3	1.0	0.5	2	4	1.2	1.0	0.4	2	6
Inhalant use days	6.0	6.0	0.0	6	1	21.0	21.0	0.0	21	1
Injection drug use days	18.0	18.0	0.0	18	1	8.0	8.0	0.0	8	1
Composite drug use daysb	23.4	8	31.8	116	34	23.7	7.0	33.7	140	34
Drug or alcohol use days	30.4	17.0	31.2	90	80	31.0	19.5	31.0	90	80

Note. Statistics are computed on users only. TLFB = Timeline Follow Back; OTC = over-the-counter

^aHeavy drinking day is defined as a day when 5 or more drinks are consumed.

^bComposite variable created by summing drug use over all substances, excluding alcohol and marijuana