Combining Subjective Perceptions and Objective Behavioral Metrics With the Elderly Digital Twin System: Quantitative Usability Study
Abstract
Background: The growing aging population has increased the need for technologies that support informal caregivers in home-based older adult care. Digital twin (DT) systems offer promising capabilities; yet, their effectiveness depends on usability, an aspect still insufficiently evaluated among caregivers. Objective: This study aimed to assess the usability of an older adult care DT system using a dual-method evaluation that integrates subjective and objective behavioral performance. Methods: Fifty caregivers participated in a usability assessment combining the System Usability Scale (SUS) and detailed system activity log analytics. Log-based measures included task completion, time on task, errors, and abandonment rate. A composite user engagement score was computed and analyzed for correlation and predictive association with SUS ratings. Engagement clusters were also explored. Results: Caregivers reported an excellent mean SUS score of 80.45. System logs showed a 94.08% task completion rate, 2.66% abandonment, and an average task duration of 89.16 seconds. User engagement score demonstrated significant correlations with SUS (r=0.626, ρ=0.552; P<.001) and significantly predicted usability in regression analysis (β=52.94, R²=0.392; P<.001). Engagement-based clustering identified high-, medium-, and low-tier user groups, each exhibiting distinct usability patterns. Conclusions: Integrating subjective usability ratings with objective behavioral metrics provides a rigorous and comprehensive approach to evaluating DT systems for older adult care. The findings highlight strong usability of the system and offer actionable insights for refining caregiver support technologies.
Authors: Ziaullah Momand, Pornchai Mongkolnam, Debajyoti Pal, Siam Yamsaengsung
Published in: JMIR Aging (2026)