usageI

UsageI is a metric framework used in human-computer interaction to quantify the efficiency and satisfaction of user interactions with digital interfaces. The I stands for interaction. It is designed to be applied across domains such as software applications, websites, and embedded interfaces, enabling comparisons between design variants and over time.

The measurement combines several observable indicators into a single index. Typical components include task success rate, time on task, error rate, feedback latency, and user-reported satisfaction. In practice, each component is normalized to a common scale, and a weighted sum yields the usageI score. The weights are chosen to reflect the study goals and context.

Data for usageI can come from usability tests, controlled experiments, field telemetry, or rapid prototyping sessions. The method supports both formative evaluation—informing design iterations—and summative assessment—comparing final designs.

Advantages include providing a holistic, comparable measure that captures both efficiency and user experience. Limitations include sensitivity to chosen weights, dependence on task selection, and potential masking of specific issues by aggregating into a single score.

An example: in evaluating two onboarding flows for a mobile app, researchers used usageI to combine completion rate, time to complete onboarding, error frequency, and user satisfaction. Flow B produced a higher usageI score, driven by faster completion and higher satisfaction, guiding final design decisions.

Related concepts include usability metrics, task success rate, cognitive load, and user satisfaction scales.