Skip Navigation LinksHome > January 2012 - Volume 23 - Issue 1 > Cell Phone Use and Crash Risk: Evidence for Positive Bias
doi: 10.1097/EDE.0b013e31823b5efc

Cell Phone Use and Crash Risk: Evidence for Positive Bias

Young, Richard A.

Supplemental Author Material



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.

Collapse Box


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.

© 2012 Lippincott Williams & Wilkins, Inc.

Twitter  Facebook 


Article Tools


Article Level Metrics