La metáfora del movimiento como la acción que configura sujetos activos y

In addition to quarters being coded for each of the seven GDL program core

components, they were also coded at a macro level to reflect the overall teen driver licensing system that was in effect in the state during each quarter. The purpose of categorizing the quarters according to the overall teen driver licensing system was to enable higher-level comparisons among: (a) 1-stage teen driver licensing systems under which young teens are allowed to apply for and obtain an unrestricted license without a learner permit holding period or intermediate licensing stage; (b) 2-stage systems with only a learner permit holding period (separately coding those lasting <3 months and those lasting ≥3 months); (c) 2-stage systems with only an intermediate licensing stage (i.e., unsupervised, but initially subject to nighttime and/or passenger restrictions, but no required learner permit holding period); (d) 3- stage GDL programs with only one driving restriction during the intermediate licensing stage (either nighttime or passenger); and (e) 3-stage GDL programs with both nighttime and passenger driving restrictions during the intermediate licensing stage.

Overall teen driver licensing systems were classified using two different coding strategies (i.e., “stronger” vs. “weaker”) meant to crudely differentiate between those that had learner permit holding periods and driving restriction components calibrated in a meaningful manner versus those in which the calibrations were likely inconsequential. For example, the length of mandatory learner permit holding periods varied across states from 7 days to 12 months. While the former is technically a learner permit holding period, it is so short that it is likely ineffectual. Passenger restriction calibrations ranged from zero passengers allowed to “no more passengers than there are seat belts” and nighttime driving restrictions ranged from “sunset to sunrise” to 1:00 am–5:00 am. Short learner permit holding periods, passenger restrictions allowing more than one teen passenger, and nighttime driving restrictions starting after midnight target only a limited scope of teen driving and therefore seem likely to have a negligible impact on crashes (Chen et al., 2000). The purpose of classifying the teen

licensing systems using two coding strategies was to be able to compare the results when stringency with respect to these three components is taken into account or ignored. The overall teen licensing system parameter estimates are considered to be meaningfully different across models if they differed by 10% or more from the stronger-coding model parameters.

Under the “stronger” coding strategy, three-stage teen licensing systems were categorized as GDL programs only if these three components were non-trivially calibrated, as defined by the following three criteria: (a) the learner permit holding period had to last at least 3 months; (b) any nighttime driving restriction had to start before 1:00 am; and (b) any passenger restriction had to allow no more than one passenger younger than age 20 in the vehicle. Under the second “weaker” coding strategy, three-stage teen licensing systems were

categorized as GDL programs regardless of how trivial the calibrations of the learner permit holding periods and nighttime/passenger driving restrictions might be. The differentiation between weaker and stronger GDL programs is not intended to suggest that 3 month or longer learner permits, nighttime driving restrictions starting before 1:00 am, and passenger restrictions allowing only one passenger are strong, good, adequate, or desirable; only that they are likely not totally inconsequential. Table 2 shows the numbers of quarters per age group and unique states contributing at least one quarter to each coded category of overall teen driver licensing system under the two coding strategies.

Table 2. Teen Driver Licensing System Categories, Number of Quarters for each Age Group in each Category, and Number of Unique States Contributing to each Category

Quarters per

age group Unique states Teen driver licensing system categories

n % n %

Stronger coding of componentsa

1-stage (no learner permit or intermediate licensing stage) 1,989 44.3 39 76.5 2-stage (learner permit holding period only < 3 months) 359 8.0 8 15.7 2-stage (learner permit holding period only ≥ 3 months) 654 14.6 20 39.2 2-stage (intermediate licensing stage only with 1–2 restrictions) 448 10.0 10 19.6 3-stage with one restriction during intermediate licensing stage (GDL) 578 12.9 24 47.0 3-stage with two restrictions during intermediate licensing stage (GDL) 460 10.2 26 51.0 Weaker coding of componentsb

1-stage (no learner permit or intermediate licensing stage) 1,989 44.3 39 76.5 2-stage (learner permit holding period only < 3 months) 359 8.0 8 15.7 2-stage (learner permit holding period only ≥ 3 months) 522 11.6 15 29.4 2-stage (intermediate licensing stage only with 1–2 restrictions) 341 7.6 8 15.7 3-stage with one restriction during intermediate licensing stage (GDL) 592 13.2 21 41.2 3-stage with two restrictions during intermediate licensing stage (GDL) 685 15.3 35 68.6

Note. Each age group had 4,488 quarters across all states and years. State percentages indicate the percentage of the 51 states contributing at least one quarter to each category across all years; the counts add to greater than 51 because some states changed categories over time. One- stage systems do not have a learner permit holding period or intermediate licensing stage. Two-stage learner permit-only systems do not have an intermediate licensing stage. Two-stage intermediate licensing stage only systems do not have a learner permit holding period. Three-stage systems with one restriction could have either a nighttime or passenger driving restriction during the intermediate licensing stage. Three-stage systems with two restrictions have both nighttime and passenger driving restrictions. GDL = Graduated driver licensing.

a_{Only learner permit holding periods lasting 3 months or longer, nighttime driving restrictions starting before 1:00 am, and passenger}

restrictions allowing no more than 1 passenger < age 20 were deemed valid for being classified as a three-stage system. b_{Any learner permit}

holding period length of time, any nighttime driving restriction, and any passenger restriction were deemed valid for being classified as a three-stage system.

17 year olds) to drive unsupervised, but initially subject to one or both of the following restrictions: (a) a nighttime driving restriction or (b) a passenger driving restriction. Under the stronger coding strategy at least one of the driving restrictions had to be non-trivial as defined above for the quarters to be classified as having intermediate licensing stages. Under the weaker coding strategy having any nighttime or passenger driving restriction that applied specifically to unsupervised 16 or 17 year olds was sufficient for quarters to be classified as having an intermediate licensing stage. However, under both strategies the “passenger

restrictions” were disregarded if they only limited the number of passengers to the number of seats or seat belts available in the vehicle or if they only applied during times when the teens were already forbidden from driving due to nighttime driving restrictions. Also excluded from this definition of an intermediate licensing stage are systems with nighttime or

passenger restrictions that applied only to learner permit holding periods, and other types of specifications such as requirements to wear seat belts or systems with only expedited post- licensing control programs (e.g., early provisional licensing programs).

One-stage licensing systems have neither a learner permit holding period nor an intermediate licensing stage. Two-stage licensing systems have either a learner permit holding period or an intermediate (unsupervised, but initially restricted) licensing stage. Two-stage learner-permit-holding-period-only systems were further divided into those with holding periods lasting less than 3 months and those with holding periods lasting 3 months or longer. The purpose of doing this was to be able to separately estimate the effects associated with short learner permit holding periods as well as those of a more substantial length. Under the stronger coding strategy the learner permit holding periods had to be non-trivial as

defined above for the quarters to be classified as having GDL programs. Under the weaker coding strategy learner permit holding periods of any length were deemed to be “a learner stage” for purposes of classifying quarters as having GDL programs. Two-stage

intermediate-stage-only systems have only an intermediate (unsupervised, but initially restricted) licensing stage with a nighttime or passenger driving restriction, as defined above under the weaker and stronger coding strategy criteria. Three-stage (GDL) programs have both learner permit holding periods and intermediate licensing stages that meet the criteria under the weaker and stronger coding strategies. These systems were further divided into those having only one driving restriction during the intermediate licensing stage (nighttime or passenger) and those having both types of driving restrictions during the intermediate

licensing stage. This was done to make it possible to separately estimate the effects associated with GDL programs with one versus two intermediate licensing stage driving restrictions.