Table 2.
Average Marginal Counts and Negative Binomial Coefficients for Past-Month Drug Use at 2- and 3-Year Follow-Up
| 2-Year Follow-Up | 3-Year Follow-Up | |||||||
|---|---|---|---|---|---|---|---|---|
| Intervention | Control | Intervention | Control | |||||
| Variable | M (SE) | M (SE) | B (SE) | IRRa | M (SE) | M (SE) | B (SE) | IRRb |
| Alcohol | 0.74 (0.09) | 0.94 (0.10) | −0.24 (0.16) | 1.29 (0.14) | 1.37 (0.14) | −0.06 (0.15) | ||
| Binge drinkingb | 0.21 (0.04) | 0.24 (0.04) | −0.12 (0.23) | 0.37 (0.06) | 0.29 (0.05) | 0.23 (0.23) | ||
| Cigarettes | 0.79 (0.22) | 1.67 (0.44) | −0.75* (0.38) | .474 | 0.75 (0.21) | 2.12 (0.57) | −1.04** (0.37) | .353 |
| e-Cigarettes | 0.59 (0.14) | 0.67 (0.15) | −0.14 (0.32) | 0.22 (0.06) | 1.49 (0.38) | −1.92*** (.38) | .146 | |
| Marijuana | 1.01 (0.21) | 1.83 (0.37) | −0.60* (0.29) | .549 | 2.46 (0.48) | 3.57 (0.68) | −0.37 (0.27) | |
| Other drugsc | 0.23 (0.06) | 0.62 (0.14) | −1.01** (0.34) | .365 | 0.21 (0.05) | 0.31 (0.07) | −0.40 (0.35) | |
Note. Average marginal counts of past-month drug use controlling for pretest score. Coefficients are adjusted for pretest score
a
Incidence rate ratio—obtained by exponentiating the coefficient—represents the proportional change in expected drug use between the intervention and control (the reference group) conditions, controlling for pretest.
b
Four or more drinks within a couple of hours.
c
Use of the following: club drugs, cocaine, ecstasy, hallucinogens, heroin, inhalants, methamphetamines, steroids, and/or prescription drugs.
*
p < .05
**
p < .01
***
p < .001