Response bias associated with asking former study participants to assist in new research

To limit research costs, former parent-participants from a completed pediatric neurology study were asked to assist with new research on behavioral contributors to childhood injury. An evaluation of the response bias associated with this recontact effort showed that 224 parents who completed the survey did not differ from the 51 who failed to complete it in race, age, education, or income. Nonresponders were significantly less likely to be married than responders.