Research In Action

Research In Action

GDL Compliance
A Novel Approach to Estimating GDL Compliance
April 19, 2016

Graduated Driver Licensing (GDL) programs—which include limitations on passengers and nighttime driving restrictions—have been proven to reduce young novice drivers’ crash risk. These restrictions are in place to help teen drivers gain driving experience in lower-risk driving situations. Yet, to be most effective, we need to fully understand the extent to which young intermediate drivers comply with these GDL restrictions. Previous studies have given us general estimates, but a more in-depth analysis is needed to best inform future improvements.

I recently published a study in Traffic Injury Prevention that proposes an alternative epidemiologic method to estimating young novices’ compliance with these restrictions, one which would allow us to test the effectiveness of policies and programs that aim to increase novice driver compliance with GDL restrictions. This alternative approach complements current methods, which include surveys, direct observations, and naturalistic studies.

This novel application of the quasi-induced exposure technique, a method used in traffic safety research to estimate driving exposure in the absence of more detailed information, such as vehicle miles driven [1,2], can overcome current methodological challenges to help answer the following questions:

  • What is the extent of non-compliance among young novice drivers?
  • How does compliance change over the course of licensure?
  • How does compliance differ by gender, age, and licensing age?
  • How does compliance differ among sociodemographic subgroups and in certain driving environments?
  • To whom should we target interventions designed to increase compliance?

What’s even more exciting: This approach can also be more broadly applied to help us estimate the extent to which certain groups of teen drivers engage in hard-to-measure risky driving behaviors, such as nighttime driving, and to evaluate the effects of interventions on these behaviors.

Importantly, researchers’ ability to do this research depends on the accuracy of data in police crash reports and the availability of licensing data (to determine a driver’s license phase).

Although it can be challenging for researchers to access identifiable traffic safety data given legislative and administrative barriers and then to utilize it due to the data’s complex administrative nature, it is well worth the effort. We need more rigorous epidemiologic methods to advance teen driver safety, and I look forward to streamlining this novel approach.


  1. Lyles, RW, Stamatiadis N, Lighthizer DR. Quasi-induced exposure revisited. Accid Anal Prev. 1991;23(4):275-285.
  2. Stamatiadis N, Deacon JA. Quasi-induced exposure: Methodology and insight. Accid Anal Prev. 1997; 29(1):37-52.