TABLE 2.
Weighted Logistic Regression Model of Ever Experimenting Among California Non-Hispanic White Female Adolescents and Adults: California Tobacco Survey, 1990–2005
| Model Variables | Coefficient (95% CI) | Between-Group Comparisons From Model | OR (95% CI) |
| Intercept | −1.56 (−1.71, 1.41) | ||
| Cohort indicators (cumulative) | Comparing successive cohorts | ||
| Born 1976–1993 (Ref) | 1.00 | Cohort 1976–1978 | 1.00 |
| Born 1979–1993 | NS | Cohort 1979–1981 versus cohort 1976–1978 | NS |
| Born 1982–1993 | −0.34 (−0.51, −0.18) | Cohort 1982–1984 versus cohort 1979–1981 | 0.71 (0.60, 0.84) |
| Born 1985–1993 | −0.42 (−0.66, −0.19) | Cohort 1985–1987 versus cohort 1982–1984 | 0.66 (0.52, 0.83) |
| Born 1988–1993 | −0.70 (−1.07, −0.34) | Cohort 1988–1990 versus cohort 1985–1987 | 0.50 (0.34, 0.71) |
| Born 1991–1993 | −1.19 (−2.06, −0.32) | Cohort 1991–1993 versus cohort 1988–1990 | 0.30 (0.13, 0.73) |
| Age indicators (cumulative) | Comparing successive ages (main effects) | ||
| 12–26 y (Ref) | 1.00 | Age 12–14 y | |
| 15–26 y | 1.32 (1.15, 1.49) | Age 15–17 y versus age 12–14 y | 3.74 (3.16, 4.44)a |
| 18–26 y | 0.78 (0.61, 0.94) | Age 18–20 y versus age 15–17 y | 2.18 (1.84, 2.56) |
| 21–26 y | −0.05 (−0.31, 0.22) | Age 21–26 y versus age 18–20 y | 0.95 (0.73, 1.25) |
| 24–26 y | −0.08 (−0.39, 0.23) | Age 24–26 y versus age 21–24 y | 0.92 (0.67, 1.26) |
| Interaction term: Born 1985–1993 × age 15–26 y | −0.30 (−0.62, −0.03) | Age 15–17 versus age 12–14 y; born < 1985 versus born ≥ 1985 | 0.74 (0.53, 0.97) |
Note. CI = confidence interval; NS = not significant; OR = odds ratio. Terms not significant at P < .25 were dropped from the model by use of backward selection, starting from a fully parameterized model. Estimates are weighted to be representative of the total population.
a
Odds ratios for cohorts born before 1985. For cohorts born 1985 or later, multiply by interaction OR.