APPENDIX B.
Summary of Peer-reviewed Papers or Technical Reports Evaluating Effects of Cellphone Bans in the United States on Crashes
| Author(s), year | Dependent measure(s) | Basic study approach | Primary study period | Main findings | Main limitations |
|---|---|---|---|---|---|
| Studies of All-Driver Hand-held Cellphone Bans | |||||
| Bhargava, Pathania, 2013 | State-level monthly rate of fatal crashes per 100,000 persons | Modeled fatal crash rate before/after bans were implemented in Connecticut, New Jersey, New York, District of Columbia, and Chicago with cellphone ownership (compared crash rates during 1989–1993, when cellphones were scarce, with rates during 2001–07) and set of control variables | 1989–2007 | No significant effect of bans on crash rates were found in full model | Although 1989–1993 is a period with far less cellphone ownership relative to 2001–07, it does not account for other period-relevant factors (e.g., vehicle safety, highway safety laws) that influence fatal crashes; unclear whether cellphone use, traffic volumes and crashes measured for same roadways and jurisdictions |
| Jacobson, King, Ryan, et al., 2012 | County-level annual rates of injury crashes per licensed drivers | Modeled crash rates in New York before/after ban, with Pennsylvania as control, for 3 driver density county groups, based on number of licensed drivers per roadway mile | 1997–2008 | Relative to changes in Pennsylvania, significant increase in injury crash rates at onset of ban for suburban/urban and very rural counties and decreasing post-ban trend in injury crash rates in urban/suburban and rural counties | No empirical or theoretical support for method of categorizing counties; mechanism underlying varying effectiveness across counties of varying driver density is unclear |
| Kolko, 2009 | State-level monthly rate of crash deaths per billion vehicle miles overall and in different conditions (e.g., wet roads, dry roads) | Modeled crash death rates with mobile phone ownership, hand-held cellphone ban status, and set of control variables across 48 contiguous states and District of Columbia | 1997–2005 | Bans not significantly associated with overall monthly crash death rate but significantly associated with lower estimated monthly crash death rates in bad weather or wet road conditions | Lack of data on vehicle miles travelled in specific driving conditions; brief post-law periods for most bans; longer term results based mainly on New York data |
| Lim, Chi, 2013a | State-level annual rates of crash deaths per miles traveled, number of drivers in fatal crashes per capita, and number of drivers in fatal crashes for 8 different age groups | Modeled crash measures with all-driver hand-held cellphone ban with primary enforcement status and set of control variables across 50 states and District of Columbia | 2000–10 | Hand-held bans with primary enforcement not significantly associated with fatality rates per miles traveled or per capita in the full models but significantly associated with reductions in total number of drivers in fatal crashes and number of drivers in fatal crashes for age groups under 55 | Reduction for youngest drivers confounded by variations in states’ teenage driver licensing laws over time; control group included states with secondary enforcement cellphone laws |
| Nikolaev, Robbins, Jacobson, 2010 | County-level and state-level annual rates of fatal crashes and injury crashes per licensed drivers | t-tests comparing mean annual crash rates in New York localities before and after ban | 1997–2007 | Significant reductions in mean crash rates in most counties and statewide | No control group or other control for crash trends unrelated to ban |
| Sampaio, 2010 | County-level annual rates of fatal crashes per licensed drivers | Modeled crash rates in New York before/after ban, with Pennsylvania as control | 1997–2007 | Reduction in fatal crash rate in New York significantly larger than reduction in Pennsylvania | Variation in county size not accounted for in model estimation |
| Trempel, Kyrychenko, Moore, 2011 | State monthly insurance collision claims per insured vehicle year | Modeled claim rates before/after bans in California, Connecticut, New York, and District of Columbia, with 2 or more neighboring control states | 18–33 months before and 12–29 months after bans effective | Nonsignificant small declines in claim rates in California and the District of Columbia relative to controls; significant small increases in Connecticut and New York | Unclear if collision claims are good indicator of distraction-related crashes, or if controls fully accounted for unobserved factors influencing claim rates |
| Studies of Texting Bans | |||||
| Abouk, Adams, 2013 | State-level monthly single-vehicle, single-occupant fatal crash counts | Modeled single-vehicle, single-occupant fatal crash counts with strong texting ban status (primary enforcement, all-driver), weak texting ban status (secondary enforcement, all-driver, or covering only young drivers), and set of control variables in 49 states (excluding Alaska) | 2007–10 | Number of single-vehicle, single-occupant fatal crashes was lower in states with strong texting bans vs. states without bans, but not significantly so in the full model; number of single-vehicle, single-occupant fatal crashes was significantly higher in states with weak bans vs. states without bans in the full model | Multiple-vehicle or multiple-occupant fatal crashes used in some analyses as control, but these crashes also could involve texting drivers; several errors in information on state ban provisions and effective dates, leading to mistakes in the classification of state bans |
| Highway Loss Data Institute, 2010 | State monthly insurance collision claims per insured vehicle year | Modeled claim rates before/after bans in California, Louisiana, Minnesota, Washington, with 2 or more neighboring control states | 6–18 months before and 12–24 after bans effective | Significant increases in claim rates in California, Louisiana, and Washington relative to controls; no significant change in claim rates in Washington | Unclear if collision claims are good indicator of distraction-related crashes, or whether controls fully accounted for unobserved factors influencing trends in claim rates |
| Studies of Multiple Types of Cellphone Bans | |||||
| Anyanwu, 2012 | State-level annual crash deaths | Modeled number of state-level annual crash deaths with hand-held cellphone ban status, texting ban status, cellphone ban for drivers under the age of 20 status, cellphone ban for intermediate license holders status, and set of control variables across 50 states and District of Columbia | 2000–09 | All-driver hand-held cellphone bans were significantly associated with fewer fatalities in the full model, but no significant effects for other types of laws | Some laws incorrectly coded based on categories described; model included only a few control variables and may not have adequately accounted for unobserved factors that influence driving habits and crash fatalities |
| Lim, Chi, 2013b | State-level number of 14–20 year-old drivers in fatal crashes not involving alcohol | Modeled number of fatal crashes with cellphone ban status for novice or young drivers with primary enforcement, all-driver hand-held cellphone ban with primary enforcement status, and set of control variables across 48 contiguous states | 1996–2010 | Significantly fewer young driver fatal crash involvements associated with all-driver hand-held phone bans with primary enforcement, but no effects found for novice or young driver bans | Changes in exposure among teenage drivers during the study period unaccounted for; states with cellphone bans with secondary enforcement included as controls; short after periods for many bans |