Background Web-based time-use diaries for schoolchildren are limited, and existing studies focus mostly on capturing physical activities and sedentary behaviors but less comprehensively on dietary behaviors. Objective This study aims to describe the development of My E-Diary for Activities and Lifestyle (MEDAL)—a self-administered, web-based time-use application to assess diet and movement behavior—and to evaluate its usability in schoolchildren in Singapore. Methods MEDAL was developed through formative research and an iterative user-centric design approach involving small groups of schoolchildren (ranging from n=5 to n=15, aged 7-13 years). To test the usability, children aged 10-11 years were recruited from 2 primary schools in Singapore to complete MEDAL for 2 weekdays and 2 weekend days and complete a 10-item usability questionnaire. Results The development process revealed that younger children (aged <9 years) were less able to complete MEDAL independently. Of the 204 participants (118/204, 57.8% boys, and 31/201, 15.4% overweight) in the usability study, 57.8% (118/204) completed 3 to 4 days of recording, whereas the rest recorded for 2 days or less. The median time taken to complete MEDAL was 14.2 minutes per day. The majority of participants agreed that instructions were clear (193/203, 95.1%), that MEDAL was easy to use (173/203, 85.2%), that they liked the application (172/202, 85.1%), and that they preferred recording their activities on the web than on paper (167/202, 82.7%). Among all the factors evaluated, recording for 4 days was the least satisfactory component reported. Compared with boys, girls reported better recall ability and agreed that the time spent on completing 1-day entry was appropriate. Conclusions MEDAL appears to be a feasible application to capture diet and movement behaviors in children aged 10-12 years, particularly in the Asian context. Some gender differences in usability performance were observed, but the majority of the participants had a positive experience using MEDAL. The validation of the data collected through the application is in progress.

BACKGROUND Web-based time-use diaries for schoolchildren are limited and exiting studies focus mostly on capturing physical activities and sedentary behaviours, but less comprehensively on dietary behaviours. OBJECTIVE In this study, we described the development of MEDAL—a self-administered, web-based time-use application to assess diet and movement behaviour, and evaluated its usability in schoolchildren in Singapore. METHODS MEDAL was developed through formative research and an iterative user-centric design approach involving small groups of schoolchildren (ranging from n=5 to 15, aged 7-13 years). To test the usability, children aged 10-11 years were recruited from two primary schools in Singapore to complete MEDAL for 2 weekdays and 2 weekend days, and a 10-item usability questionnaire. RESULTS The development process revealed that younger children (<9 years) were less able to complete MEDAL independently. Of 204 participants (58% boys and 15% overweight) in the usability study, 58% of them completed 3-4 days of recording while the rest recorded 2 days or less. The median time taken to complete MEDAL was 14.2 min/day. Majority agreed that instructions were clear (95%), that MEDAL was easy to use (85%), that they liked the application (85%), and preferred recording their activities online than on paper (83%). Recording for 4 days was the least satisfactory component reported. Compared to boys, girls reported better recall ability and agreed that the time spent on completing 1-day entry was appropriate. CONCLUSIONS MEDAL appears to be a feasible application to capture diet and movement behaviours for children aged 10 years and above, particularly in the Asian context. Some gender differences in usability performance were observed but the majority of the participants had a positive experience using MEDAL. Validation of data collected through the application is in progress.