TABLE 2—
Regression-Discontinuity Models for Motor Vehicle Accidents, Suicides Related to Alcohol, and External Injuries: Young Women and Men in Ontario, 2002–2007
| Motor Vehicle Accidents |
Suicides Related to Alcohol |
External Injuries |
|||||||
| Total | Female | Male | Total | Female | Male | Total | Female | Male | |
| Linear, b (95% CI) | −0.62 (−1.59, 0.35)a | −0.54 (−1.86, 0.79)a | −0.64 (−2.04, 0.75)a | 0.10** (0.03, 0.18)a | 0.17** (0.06, 0.28)a | 0.02 (−0.07, 0.12)a | 0.19 (−2.00, 2.38) | −3.00* (−5.34, −0.66) | 4.33* (1.01, 7.64)a |
| Quadratic, b (95% CI) | −0.26 (−1.79, 1.28) | 0.31 (−1.78, 2.40) | −0.80 (−3.06, 1.45) | 0.10 (−0.02, 2.13) | 0.24** (0.07, 0.41) | −0.07 (−0.21, 0.07) | 2.26 (−0.95, 5.48)a | 1.39 (−1.90, 4.68)a | 5.13 (−0.04, 1.03) |
| Cubic, b (95% CI) | −0.76 (−3.03, 1.51) | −0.21 (−3.26, 2.84) | −1.32 (−4.59, 1.94) | 0.05 (−0.12, 0.21) | 0.21 (−0.04, 0.45) | −0.15 (−0.35, 0.05) | 2.74 (−1.84, 7.32) | 2.26 (−2.42, 6.95) | 6.16 (−1.21, 1.35) |
| Bandwidth, b (95% CI) | |||||||||
| 3 | −2.87*** (−2.89, −2.85) | −3.35*** (−4.25, −2.46) | −2.30*** (−3.37, −1.23) | 0.13*** (0.08, 0.17) | 0.29*** (0.18, 0.40) | −0.06 (−0.29, 0.17) | 9.46*** (8.34, 10.58) | 4.32*** (3.04, 5.61) | 15.52*** (14.58, 16.45) |
| 5 | −1.24 (−2.75, 0.28) | −1.31 (−3.20, 0.59) | −1.14 (−2.49, 0.22) | 0.02 (−0.10, 0.13) | 0.12 (−0.19, 0.42) | −0.10 (−0.34, 0.142) | 8.00*** (5.03, 10.98) | 5.24*** (2.94, 7.84) | 11.75*** (5.25, 18.25) |
| 10 | −0.10 (−1.84, 1.63) | −0.19 (−2.12, 1.73) | 0.06 (−1.74, 1.87) | 0.03 (−0.06, 0.13) | 0.14 (−0.08, 0.35) | 0.89 (−0.32, 0.14) | 5.51*** (2.39, 8.62) | 3.35** (1.17, 5.54) | 9.75*** (5.71, 13.80) |
| 20 | −0.28 (−1.40, 0.85) | 0.17 (−1.14, 1.48) | −0.74 (−2.18, 0.70) | 0.09* (0.03, 0.32) | 0.18* (0.03, 0.32) | −0.01 (−0.15, 0.13) | 3.63** (0.15, 5.98) | 1.60 (−0.56, 3.75) | 6.06** (1.51, 10.62) |
| Intercept | |||||||||
| Linear | 27.39 | 25.4 | 29.7 | 0.19 | 0.18 | 0.207 | 161.49 | 111.2 | 220.44 |
| Quadratic | 26.81 | 24.52 | 29.47 | 0.14 | 0.12 | 0.173 | 158.83 | 107.66 | 218.79 |
| Cubic | 27.02 | 25.36 | 28.93 | 0.19 | 0.18 | 0.189 | 158.4 | 107.2 | 218 |
| Effect,b % | |||||||||
| Linear | −2.3a | −2.1a | −2.2a | 51.8a | 91.8a | 11.6a | 0.1 | −2.7 | 2.0a |
| Quadratic, | −1.0 | 1.3 | −2.7 | 68.5 | 204.7 | −39.9 | 1.4a | 1.3a | 2.3 |
| Cubic | −2.8 | −0.8 | −4.6 | 25.3 | 112.0 | −77.2 | 1.7 | 2.1 | 2.8 |
| Optimum bandwidthc | 6.7 | 6.7 | 6.9 | 2.5 | 2.8 | 3.8 | 8.1 | 8.9 | 7.3 |
| Optimum bandwidth result, b (95% CI) | −0.08 (−2.40, 2.24) | −0.33 (−2.71, 2.05) | 0.36 (−2.12, 2.85) | 0.13*** (0.10, 0.16) | 0.29*** (0.19, 0.39) | −0.11 (−0.33, 0.12) | 6.49*** (3.50, 9.49) | 3.71*** (1.43, 5.99) | 11.42*** (8.05, 14.80) |
| No. of eventsd | 1154 | 585 | 569 | 11 | 5 | 6 | 7033 | 2568 | 4465 |
Note. CI = confidence interval. Values are the coefficients of the minimum legal drinking age (MLDA) indicators in the regression model and, therefore, indicate the change in hospital events per 1000 admissions among youths at the MLDA threshold. Bandwidths refer to the bandwidth values used in the local regression models. Bandwidths of 3, 5, 10, and 20 represent the approximate multiples used (approximately 6 across models). The age range was 16 to 22 years for all outcomes, except for motor vehicle accidents for which the age range was 17 to 21 years.
Results from the best parametric regression model.
Percentage change in hospital events among youths at the MLDA threshold (the coefficient of the MLDA indicator divided by the intercept of the model).
A parameter indicating the best set of points to be used in the local linear regression to minimize error variance.
Unadjusted count of outcome events appearing in the age category immediately following the minimum legal drinking age. For example, in the first column, there are 1154 motor vehicle accidents in the age category including ages from the MLDA up to 1 month after the MLDA.
*P ≤ .05; **P ≤ .01; ***P ≤ .001.