7 The panel is continuously replenished and maintains about 55 000 panellists. A total of 8110 adults completed the spring survey for a response rate of 56%. Then, from 16 July to 3 August 2011, the YouthStyles survey was sent to a random sample of 1614 potential respondents aged 12–17 years living in households in which a parent had participated in the 2011 spring HealthStyles survey; 840 52% youth participated. Seven participants did not answer the ATV riding question and were excluded, leaving 833 respondents. Porter Novelli provided the Centers for Disease Control and Prevention CDC with both unweighted and weighted data from the 2011 YouthStyles survey; the data were weighted to match the 2010 US Census benchmarks for age, race, gender, household income, number of youth aged 12–17 years in household, education, census region, metropolitan statistical area MSA status and internet access personal communication, Deanne Weber of Porter Novelli, 2012. 7 Institutional review board approval was not required for this study because Porter Novelli provided the CDC with a final, de identified data set. Respondents who rode an ATV at least once during the past 12 months were then asked, “How often do you wear a helmet when you ride or drive an ATV?” Response options included ‘always’; ‘nearly always’; ‘sometimes’; ‘seldom or rarely’ or ‘never’. Responses were first grouped into the following four categories: always; nearly always or sometimes; seldom or rarely; and never, and helmet use among all riders was reported using all four categories. Due to small cell sizes, for subsequent cross tabulations, helmet use was dichotomised as either always or not always including nearly always, sometimes, seldom or rarely, and never. Frequency distributions of ATV riding were calculated for riders overall and by gender, geographic region and MSA status. Frequency distributions of helmet use were calculated for riders overall and by gender, MSA status and riding frequency.

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