Three items assess how easy a branded mobile app is to understand and operate. This scale is one of five subscales developed by Baek and Yoo (2018) as part of a comprehensive branded app usability instrument. AVE was .83; convergent, discriminant, and nomological validity were supported.
Baek, T. H., & Yoo, C. Y. (2018). Branded app usability: Conceptualization, measurement, and prediction of consumer loyalty. Journal of Advertising, 47(1), 70–82.
Free access to 2023+ psychometric scales at PsychScales