Institutional members access full text with Ovid®

Share this article on:

Cell Phone Use and Crash Risk: Evidence for Positive Bias

Young, Richard A.



Young RA. Cell phone use and crash risk: Evidence for positive bias. Epidemiology. 2012;12:116–118.

On page 118, left column, line 8, the sentence should say “with >0% consistency,” not “with 70% consistency.”

Epidemiology. 23(2):358, March 2012.

doi: 10.1097/EDE.0b013e31823b5efc

Background: Recent epidemiologic studies have estimated little or no increased risk of automotive crashes related to cell phone conversations by the driver, whereas earlier case-crossover studies estimated the relative risk as close to 4. Did earlier studies introduce a positive bias in relative risk estimates by overestimating driving exposure in control windows?

Methods: Driving exposures in a “control” window and a corresponding “case” window on the subsequent day were tabulated across 100 days for 439 GPS-instrumented vehicles in the Puget Sound area during 2005–2006.

Results: For control windows containing at least some driving, driving exposure was about one-fourth that of case windows. Adjusting for this imbalance reduces relative risk estimates in the earlier case-crossover studies from 4 to 1.

Conclusion: Earlier case-crossover studies likely overestimated the relative risk for cell phone conversations while driving by implicitly assuming that driving during a control window was full-time when it may have been only part-time.

Supplemental Digital Content is available in the text.

From the Department of Psychiatry and Behavioral Neurosciences, Wayne State University School of Medicine, Detroit, MI.

Submitted 14 February 2011; accepted 9 September 2011; posted 14 November 2011.

The author reported no financial interests related to this research.

Supplemental digital content is available through direct URL citations in the HTML and PDF versions of this article (available at:

Correspondence: Richard A. Young, Department of Psychiatry and Behavioral Neurosciences, Wayne State University School of Medicine, 9B-19 University Health Center, 4201 St. Antoine, Detroit, MI 48201. E-mail:

Copyright © 2012 Wolters Kluwer Health, Inc. All rights reserved.