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. Author manuscript; available in PMC: 2013 Mar 14.
Published in final edited form as: Traffic Inj Prev. 2011 Oct;12(5):423–431. doi: 10.1080/15389588.2011.588296

Table 3.

Coefficients from time-series regression models testing the effects of the passage of GDL lawsa on the variance of age group ratios. Coefficients indicate variance attributable to GDL laws alone and in the presence of selected covariates.

Age ratio Model Any GDL lawa Good GDL lawsa < Good GDL lawsa
coeff P coeff P Coeff P
16–17/19–20 GDL alone −0.089 0.0001 −0.112 0.0003 −0.061 0.1016
GDL with all covariates −0.081 0.0057 −0.123 0.0012 −0.010 0.8320
 GDL with SBb −0.065 0.0058 −0.094 0.0018 −0.030 0.4369
 GDL with ZTb −0.117 <.0001 −0.144 <.0001 −0.070 0.1207
 GDL with .08 limitb −0.077 0.0054 −0.110 0.0034 −0.010 0.8134
 GDL with Use & Loseb −0.078 0.0011 −0.099 0.0017 −0.047 0.2282
16–17/21–25 GDL alone −0.108 <.0001 −0.104 0.0018 −0.120 0.0052
GDL with all covariates −0.070 0.0265 −0.094 0.0186 −0.027 0.6095
 GDL with SBb −0.080 0.0028 −0.080 0.0196 −0.088 0.0458
 GDL with ZTb −0.118 <.0001 −0.136 0.0003 −0.075 0.1456
 GDL with .08 limitb −0.079 0.0085 −0.088 0.0257 −0.052 0.2740
 GDL with Use & Loseb −0.097 0.0003 −0.088 0.0106 −0.117 0.0102
a

Three levels of GDL laws were tested: “Any,” “Good,” and “< Good.” GDL laws were rated by the by the IIHS as good, fair, marginal or poor, in descending order. “Any” refers to all GDL laws regardless of rating. “Good” refers to only GDL laws rated good. “<Good” refers to GDL laws in which those rated good were excluded from analysis.

b

SB=states with primary enforcement seatbelt laws; ZT=states with laws for zero tolerance of any alcohol for drivers <21 years in which driver’s license is forfeited; .08=states with a blood alcohol concentration legal limit of .08 g/dL for all drivers; Use & Lose=states with laws in which persons <21 years caught with alcohol in any situation forfeit their driver’s license.