Usability

A digital system can be technically flawless, visually refined, rich in features. Yet if a user cannot complete an operation smoothly, the system has failed its fundamental purpose. The difference between a system that works and one that truly works has a name: usability.

The ISO 9241-11:2018 standard defines usability as the extent to which a system, product or service can be used by specified users to achieve specified goals with effectiveness, efficiency and satisfaction in a specified context of use.

Three dimensions worth unpacking

Effectiveness is the capacity of the system to allow users to achieve their goals completely and accurately. Did the user find what they were looking for? Did they complete the operation they intended to carry out?

Efficiency concerns the resources consumed to reach that goal: the time spent, the errors made, the number of steps required. A system can be effective but inefficient — the goal is reached, but with excessive effort.

Satisfaction is the subjective dimension: the comfort, the absence of discomfort, the overall judgement of the experience. A system can be effective and efficient and yet leave the user with a sense of frustration or disorientation.

These three dimensions do not operate in isolation: they influence one another and all depend on the context of use — the specific combination of users, tasks, physical environment and technological environment in which the interaction takes place. The same system can prove highly usable in one context and problematic in another.

Usability is not a product attribute: it is a relationship

One of the most common mistakes in the way usability is understood is treating it as an intrinsic property of a system — something the product either possesses or does not, independently of who uses it and in what situation.

Research and international standards have made clear that this is not the case. Usability is not a static characteristic of the interface: it is the dynamic result of the interaction between a real user, with their own skills, expectations and goals, and a system, in a given context. Change the user, change the context, and usability changes too — even if the product remains identical.

How Esario evaluates and designs for usability

Esario's approach is structured across three complementary levels, consistent with the integrated evaluation model recognised by the international research community.

Expert evaluation

The first level is the analysis conducted by experts on the interface, independently of users. This is an objective assessment of the system's conformance to established principles, standards and guidelines: heuristic analysis, cognitive walkthroughs, verification of conformance with accessibility and dialogue standards. This level makes it possible to identify structural errors in the interface design — problems that stem from design choices and that, if left uncorrected, will produce interaction difficulties for any user.

Testing with real users

The second level brings real users to interact with the system in structured test sessions, while an evaluator observes and measures. This level produces direct data on effectiveness, efficiency and the interaction problems actually experienced — distinct from the errors identified in the expert analysis. The distance between the two sets of findings is itself a valuable measure: it reveals the gap between the system imagined by the designer and the system as perceived by the real user.

Measuring satisfaction

The third level completes the picture with the collection of qualitative and psychometric data on user satisfaction. Standardised questionnaires and structured interviews make it possible to quantify the subjective dimension of the experience — that component which neither expert analysis nor behavioural observation can fully capture.

Esario applies this approach across the Hotels, E-Commerce, Finance and Bio-Medical sectors, adapting methods, user profiles and metrics to the specific characteristics of each domain. A financial portfolio management application and a hotel booking system require deeply different usability criteria and test populations: Esario understands these differences and places them at the centre of every evaluation.

Usability and Artificial Intelligence

Artificial Intelligence is significantly transforming the way it is possible to design, evaluate and improve the usability of a digital system — in the analysis phase, in testing, and in continuous monitoring after release.

In the preliminary analysis phase, AI models make it possible to process large volumes of behavioural data — navigation logs, session recordings, support interaction transcripts — to identify recurring patterns of difficulty, drop-off points, and error sequences that signal systemic usability problems. Work that would require weeks of manual analysis can today be processed in significantly less time, with a statistical coverage impossible to achieve through traditional methods alone.

In the conduct of testing, AI-assisted eye-tracking tools, automated facial expression analysis and motor behaviour classifiers make it possible to collect objective data on the user's response to the interface with a degree of granularity previously out of reach. Not only what the user does is measured, but where they look, how long they hesitate, when they display signs of frustration — all in an automated and scalable way.

In heuristic testing, Large Language Models can now simulate user journeys, identify potential violations of usability principles and produce structured reports on interface issues — reducing the time required for expert analysis while increasing its systematicity.

In live systems, AI-based continuous monitoring makes it possible to detect usability regressions in real time — when an update introduces new interaction difficulties, before these translate into measurable drop-offs or user complaints.