Table 2.
The item response theory analysis of past-year DSM-IV alcohol- and marijuana-dependence symptoms
| Symptoms of dependence | Alcohol users (n = 462) |
Marijuana users (n = 311) |
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| Prev.% | Factor loadings | Item discrim. (SE) | Item severity (SE) | Prev. % | Factor loadings | Item discrim. (SE) | Item severity (SE) | |
| D1: Tolerance | 40.3 | .89 | 1.80 (0.14) | 0.28 (0.07) | 34.1 | .80 | 1.51 (0.12) | 0.52 (0.09) |
| D2: Withdrawal | 24.5 | .90 | 1.88 (0.16) | 0.82 (0.07) | 16.7 | .78 | 1.61 (0.13) | 1.17 (0.10) |
| D3: Taking larger amounts | 34.8 | .93 | 1.98 (0.17) | 0.45 (0.07) | 31.8 | .91 | 1.79 (0.16) | 0.58 (0.09) |
| D4: Unable to cut down | 44.4 | .87 | 1.79 (0.13) | 0.15 (0.06) | 39.9 | .82 | 1.60 (0.13) | 0.33 (0.09) |
| D5: Time spent using or recovering | 30.5 | .95 | 2.03 (0.18) | 0.59 (0.07) | 32.2 | .92 | 1.84 (0.17) | 0.56 (0.09) |
| D6: Giving up activities | 31.2 | .97 | 2.16 (0.21) | 0.56 (0.07) | 21.9 | .90 | 1.80 (0.17) | 0.92 (0.10) |
| D7: Continued use despite having problems | 37.2 | .92 | 1.97 (0.17) | 0.37 (0.07) | 21.5 | .84 | 1.66 (0.14) | 0.95 (0.10) |
Notes: DSM-IV = Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition; prev. = prevalence; discrim. = discrimination; D = dependence symptoms.