Table 5.

Digit symbol substitution task: Multilevel model of marijuana high in relation to reaction time.

Effects			DSSTa reaction time (n=60)
			Estimate	SE	95% CI	P value
Fixed effects
	Person level (level 2)
		Intercept	2328.14	233.72	N/Ab	.001c
		Session	−9.45	0.45	N/A	.001c
		Session2 (quadratic)	0.12	0.01	N/A	.001c
		Subjective high (PMd)	181.32	55.83	N/A	.001c
		Distraction (PM)	−441.54	179.82	N/A	.01e
		Subjective high (PM) × distraction (PM)	−109.72	42.5	N/A	.01e
		Gender (0=male, 1=female)	−2.75	31.61	N/A	.93
		Age (0=age 20)	7.55	8.92	N/A	.4
		Full-scale IQ (0=IQ score of 110)	4.91	3.02	N/A	.1
	Session level (level 1)
		Subjective high (CCf)	3.08	1.41	N/A	.03e
		Distraction (CC)	2.21	4.6	N/A	.63
		Subjective high (CC) × distraction (CC)	−1.01	0.92	N/A	.27
Random effects
	Level 1 residual variance		9950.65	285.83	9405.91 to 10,526.95	N/A
	Intercept		12906.21	2506.7	8820.12 to 18,885.27	N/A
	Distraction		63.55	59.06	10.28 to 392.83	N/A
	Covariance (distraction, intercept)		−67.68	330.49	−715.43 to 580.07	N/A

^aDSST: digit symbol substitution task.

^bNot applicable.

^cP<.01.

^dPM: person mean scores, reflecting individual differences in subjective marijuana high or distraction across all sessions.

^eP<.05.

^fCC: constant-centered scores (centered at 0), reflecting session-to-session variation in scores or session-specific scores.