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. Author manuscript; available in PMC: 2010 Aug 1.
Published in final edited form as: Drug Alcohol Depend. 2009 May 6;103(3):114–123. doi: 10.1016/j.drugalcdep.2009.01.018

Table 2.

Factor loadings and IRT discrimination and severity estimates of past year DSM-IV cocaine and opioid dependences

Symptoms of dependence Cocaine users (N = 366) Opioid users (N = 354)
Prevalence Factor loadings Item discrimination
(S.E.)		 Item severity
(S.E.)		 Prevalence Factor loadings Item discrimination
(S.E.)		 Item severity
(S.E.)
D1: Tolerance 69.4 0.77 1.12
(0.18)		 −0.66
(0.12)		 81.6 0.77 1.22
(0.23)		 −1.18
(0.16)
D2: Withdrawal 44.3 0.65 0.86
(0.14)		 0.24
(0.10)		 85.0 0.80 1.36
(0.23)		 −1.30
(0.17)
D3: Taking larger amounts 62.0 0.80 1.45
(0.25)		 −0.33
(0.09)		 63.0 0.86 1.79
(0.31)		 −0.38
(0.08)
D4: Unable to cut down 77.6 0.86 1.43
(0.22)		 −0.91
(0.12)		 77.7 0.84 1.53
(0.27)		 −0.91
(0.11)
D5: Time spent using or recovering 60.7 0.90 2.44
(0.62)		 −0.24
(0.08)		 72.6 0.79 1.27
(0.24)		 −0.77
(0.12)
D6: Giving up important activities 56.0 0.77 1.29
(0.21)		 −0.16
(0.09)		 54.2 0.88 2.18
(0.42)		 −0.12
(0.07)
D7: Continued use despite having problems 61.5 0.72 1.04
(0.17)		 −0.38
(0.11)		 57.6 0.73 1.19
(0.18)		 −0.25
(0.09)

IRT = item response theory; S.E. = standard error.