Definition

Item

Source

The effectiveness, efficiency and satisfaction with which specified users can achieve specified goals in particular environments. Effectiveness is defined as “the accuracy and completeness with which users achieve specified goals” and efficiency as “the resources expended in relation to the accuracy and completeness with which users achieve goals” (IS0 DIS 9241-11)

I use my phone frequently

Brooke (1986) [41]

I find my phone simple to use

I can effectively complete my work using my phone

I find my phone easy to learn