An Evaluation of the Use of Odds Ratios to Estimate the Association between Mobile Phone Use and Safety Critical Driving Events

Reed, Nick; Cynk, Charlene Hallett Stephanie; Jenkins, David · 2022 · Crossref

DOI: 10.54941/ahfe100758

archive: archived pipeline: cataloged verified

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Summary

This paper evaluates the validity of using odds ratios to estimate the association between mobile phone use and safety-critical driving events (SCEs), addressing discrepancies between naturalistic driving studies and laboratory or epidemiological findings. While laboratory studies consistently show that mobile phone use impairs driving performance, previous naturalistic studies (e.g., Hickman et al., 2010) reported counterintuitive results, such as hands-free phone use having a "protective" effect (odds ratio < 1). The authors sought to determine if these findings were robust or artifacts of data collection and analysis methods. The study utilized a large dataset from SmartDrive, an in-vehicle camera and telematics system, covering 23,472 vehicles across the USA, UK, and New Zealand from April 2012 to October 2013. The system recorded 30-second epochs triggered by kinematic events (e.g., harsh braking, acceleration). Trained observers coded these epochs as either SCEs (near-crashes) or baseline epochs (BEs). Due to legal liability constraints, collision data was excluded, leaving 9,723 SCEs and 89,167 BEs for analysis. The authors calculated odds ratios for various mobile phone tasks, including handheld use, hands-free use, and texting/dialling, using statistical methods consistent with prior naturalistic driving research. The results revealed that all mobile phone-related tasks were associated with significant odds ratios less than 1.00. Specifically, hands-free mobile phone use had an odds ratio of 0.27, handheld use was 0.34, and texting/dialling was 0.46. These findings suggest that drivers engaged in these tasks were significantly less likely to be involved in an SCE compared to baseline driving. Notably, the result for texting/dialling contradicts established literature indicating high risk, a discrepancy the authors attribute to the small number of events (22 SCEs) and potential biases in the dataset. The authors conclude that the use of odds ratios on event-triggered naturalistic data may produce misleading results due to methodological limitations. Key issues include the exclusion of collision data, the inability to distinguish between sub-tasks (e.g., dialing vs. talking), and the fact that drivers who trigger recording devices are often safer drivers overall. The study argues that while in-vehicle data recorders are valuable for fleet management, their data may not be suitable for accurately quantifying distraction risks via odds ratios. The findings highlight the need for caution when interpreting naturalistic driving data and suggest that current methods may fail to capture the true risk associated with secondary tasks.

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Summary generated by qwen3.6-27b-prismaquant on 2026-06-25; verification: verified.

Topics

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• mobile phones
• distraction laws
• visual manual
• naturalistic crash near crash
• exposure measurement
• manual

Information type

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• Empirical Findings: observational prevalence, crash risk outcomes
• Methodological Resource: dataset resource