title: A validity study of self-reported daily texting frequency, cell phone characteristics, and texting styles among young adults.
abstract: BACKGROUND
  Texting is associated with adverse health effects including musculoskeletal disorders, sleep disturbances, and traffic crashes. Many studies have relied on self-reported texting frequency, yet the validity of self-reports is unknown. Our objective was to provide some of the first data on the validity of self-reported texting frequency, cell phone characteristics including input device (e.g. touchscreen), key configuration (e.g., QWERTY), and texting styles including phone orientation (e.g., horizontal) and hands holding the phone while texting.
  
  
  METHODS
  Data were collected using a self-administered questionnaire and observation of a texting task among college students ages 18 to 24. To gauge agreement between self-reported and phone bill-derived categorical number of daily text messages sent, we calculated percent of agreement, Spearman correlation coefficient, and a linear weighted kappa statistic. For agreement between self-reported and observed cell phone characteristics and texting styles we calculated percentages of agreement. We used chi-square tests to detect significant differences (α = 0.05) by gender and study protocol.
  
  
  RESULTS
  There were 106 participants; 87 of which had complete data for texting frequency analyses. Among these 87, there was 26% (95% CI: 21-31) agreement between self-reported and phone bill-derived number of daily text messages sent with a Spearman's rho of 0.48 and a weighted kappa of 0.17 (95% CI: 0.06-0.27). Among those who did not accurately report the number of daily texts sent, 81% overestimated this number. Among the full sample (n = 106), there was high agreement between self-reported and observed texting input device (96%, 95% CI: 91-99), key configuration (89%, 95% CI: 81-94), and phone orientation while texting (93%, 95% CI: 86-97). No differences were found by gender or study protocol among any items.
  
  
  CONCLUSIONS
  While young adults correctly reported their cell phone's characteristics and phone orientation while texting, most incorrectly estimated the number of daily text messages they sent. This suggests that while self-reported texting frequency may be useful for studies where relative ordering is adequate, it should not be used in epidemiologic studies to identify a risk threshold. For these studies, it is recommended that a less biased measure, such as a cell phone bill, be utilized.
authors.affiliation: Department of Public Health, Temple University, 1301 Cecil B. Moore Ave., Philadelphia, PA, USA. Judith.Gold@hig.se.|West Virginia University Injury Control Research Center, PO Box 9151, Morgantown, WV, USA. Judith.Gold@hig.se.|Centre for Musculoskeletal Research, University of Gävle, Gävle, Sweden. Judith.Gold@hig.se.
authors.forename: Judith E
authors.initials: JE
authors.lastname: Gold
authors.affiliation: West Virginia University Injury Control Research Center, PO Box 9151, Morgantown, WV, USA. krauscher@hsc.wvu.edu.|Department of Occupational and Environmental Health Sciences, West Virginia University School of Public Health, PO Box 9190, Morgantown, WV, USA. krauscher@hsc.wvu.edu.
authors.forename: Kimberly J
authors.initials: KJ
authors.lastname: Rauscher
authors.affiliation: West Virginia University Injury Control Research Center, PO Box 9151, Morgantown, WV, USA. mozhu@hsc.wvu.edu.|Department of Epidemiology, West Virginia University School of Public Health, PO Box 9190, Morgantown, WV, USA. mozhu@hsc.wvu.edu.
authors.forename: Motao
authors.initials: M
authors.lastname: Zhu
mesh_terms: D000328:Adult; D040421:Cell Phone; D005260:Female; D006801:Humans; D008297:Male; D011795:Surveys and Questionnaires; D060145:Text Messaging; D055815:Young Adult