Measurements
Our questionnaire evaluated three groups of variables, including basic and demographic variables, exposures, and outcomes.The demographic variables included age (years), gender (male or female), educational level (level one high school or level two high school), body mass index (BMI), and family structure (living with both parents, father, mother, or other relatives). Level one high school equals 7 to 9 years of education, and level two high school equals 10 to 12 years of education in Iran. The exposures (independent variable) included types of ICTs (e.g., mobile phone, tablet, PlayStation 4, laptop, and computer), position using electronic devices (sitting at the table, sitting on the floor, and lying), and the average amount of time they spent with each ICT per day in the past week (1. I do not use, 2. less than 3 h per day, 3. between 3 and 6 h per day, 4. more than 6 h per day). The outcome was any episodes of neck pain in the past week, as reported by the participants.