Testing Digital Technologies to Help Families Build Healthy Habits

The System Usability Scale (SUS) was used to measure usability of the intervention. The items were adapted so that the caregiver could report on their child's experience of usability. SUS consists of 10 items with five response options on a Likert scale: strongly disagree (0) to strongly agree (4). SUS yields a single number representing a composite measure of the overall usability of a system being studied, ranging from 1 to 100, with greater scores reflecting greater usability, and calculated as follows (Brooke, 1996): "Each item's score contribution will range from 0 to 4. For items 1,3,5,7,and 9 the score contribution is the scale position minus 1. For items 2,4,6,8 and 10, the contribution is 5 minus the scale position. Multiply the sum of the scores by 2.5 to obtain the overall score."

The Usefulness, Satisfaction and Ease of Use Questionnaire was used to measure acceptability, specifically usefulness, ease of use, ease of learning, and satisfaction with an intervention or service. Items were adapted to have the caregivers report on their child's experience of usability. The shortened instrument used in this study (Lund, 2001) contains 19 items, and respondents indicate their agreement with each statement on a scale from 1 (strongly disagree) to 7 (strongly agree). Scores are summed to create an overall score of usability, ranging from 19 to 133, with greater scores indicating greater usability.

Degree of Immersion in the virtual environment is assessed by parent self-report with the Presence Questionnaire (Witmer 2005). The Presence Questionnaire is a 24 item questionnaire that assesses involvement, auditory fidelity, adaption/immersion, interface quality, consistency with expectations, and haptic/visual fidelity. Given that sense of touch was not applicable to the present study, this item (23) was not included in the final score. Responses to the items are on a scale from 1 (not at all) to 7 (completely), and responses are summed to create an overall score. Potential scores range from 23 to 161, with greater scores indicating greater self-reported feelings of being immersed in the virtual environment.

Assessed with child interview questions created by the study team. Questions ask children to respond by indicating which smiley face on a 5 point analog scale best represents how they feel, from 1 (unhappy/not at all) to 5 (very happy/a lot). Acceptability was assessed by asking how much the child liked the intervention, and motivation was assessed by asking the child how motivated they are to eat healthier post-intervention. Greater numbers on each question represent greater acceptability and greater post-intervention motivation, respectively.

Child self-report survey measure. The Self-Efficacy for Healthy Eating and Physical Activity (SE-HEPA) measure was developed by Steele, Bindler, Power, and Daratha (2008) and is based on Motl et al.'s (2000) unidimensional measure of self-efficacy for exercise. Based on Bandura's (1977) social cognitive theory, SE-HEPA was designed to evaluate a children's or adolescents' confidence in their ability to engage in healthy eating (8 items) and physical activity behaviors (8 items). Items are answered on 5 point Likert scales from strongly disagree (1) to strongly agree (5). Scores are summed to create two subscales: self-efficacy for healthy eating, and self-efficacy for physical activity. Possible scores for each subscale range from 8 to 40, with greater scores indicating greater self-efficacy.

The caregiver Readiness to Change Diet and Physical Activity items were adapted from previously used questions and designed to assess caregiver readiness to help their child change physical activity and eating behaviors. Parents self-report their intentions to help their children with healthy habits by answering "Do you intend to find ways to improve the way your child eats?" and "Do you intend to find ways to improve your child's physical activity level?" with responses from 1 ("No, and I'm not intending to make changes"), 2 ("Yes, I intend to make changes in the next 6 months"), 3 ("Yes, I intend to make changes in the next month"), to 4 ("I'm already helping my child improve their [eating/activity]"). Scores range from 1 to 4, with greater scores indicating greater caregiver readiness to help their child change. Items are not aggregated, and each item is analyzed separately.

Behavioral beliefs (attitudes) and intentions toward health eating were measured with items adapted from previous literature based on the Theory of Planned Behavior. Where needed, language was adapted to lower the reading level for child participants. Items were answered on 7 point Likert scales from strongly disagree (1) to strongly agree (7). Scores were summed for child attitudes (beliefs), child intentions, and caregiver intentions, self-reported by children and caregivers pre- and post-intervention. Eight items measured child attitudes towards eating healthy, with total scores ranging from 8 to 56, and greater scores indicating more positive attitudes toward eating healthier.

Six items measured child intentions toward healthy eating, with total scores ranging 6 to 42, and greater scores indicating greater intentions to engage in the behavior.

Four items measured caregiver intentions to help child, with total scores ranging from 4 to 28, and greater scores indicating gre

Parents reported on their child's eating behavior of the previous week with three different items asking parents to report the number of servings per week the child ate of fruits, vegetables, and fast foods.

Parents reported on their child's eating behavior of the previous week with two different items asking parents to report the number of days per week the child ate breakfast and family dinner.

Parents reported on their child's activity behavior of the previous week with two different items asking parents to report the average number of hours per day the child engaged in screen time and physical activity, on a scale from 1 to 5, with 1 = none; 2 = less than 1 hour per day; 3 = 1 to 2 hours per day; 4 = 3 to 4 hours per day; 5 = more than 4 hours per day.