Usability: 3 Key Factors to Assess Your Product Design


What exactly do we mean when we talk about a product or service’s “usability”? Clearly, it has something to do with how usable it is. (So far, that’s a pretty recursive definition!). But what makes something usable? At the highest level, product and user experience (UX) designers determine usability based on three factors:

  • Effectiveness: Can people do what they set out to do?
  • Efficiency: Can people do what they need to do within a reasonable amount of time/effort to make it worth doing?
  • Satisfaction: Do people feel OK about what they had to do in order to properly use it?

This is a big deal, and there’s even a specific standard (ISO 9241-11) set forth by the International Organization for Standardization that defines usability as “the extent to which a product can be used by specified users to achieve specified goals with effectiveness, efficiency and satisfaction in a specified context of use.”

Therefore, usability is about matching products, systems, and services to users’ needs and requirements.

Usability vs. Functionality

When we, as members of a project team, focus on usability (and we should always focus on usability), we’re concerned with supporting people in accomplishing their tasks. This shouldn’t be confused with “functionality,” however, as the mere presence of good features and functions has little bearing on whether people are able to use them.

When we overload products or services with too many features, or when we provide them in ways that don’t match people’s expectations or needs, it’s difficult for people to access what’s needed when they need it, let alone use it once they do find it. When that happens, people end up fumbling with the product or service rather than achieving their goals. They are very likely to abandon what they’re doing, or find another way to achieve that goal.

Think of it this way: People don’t use ATMs for the sake of interacting with a machine on a wall. They use them (predominantly) because they want some cash. To design an ATM — or any product — that’s as usable as possible, we need to consider a number of factors:

  • Who are the users? They’re people who are not going to be “trained” in using an ATM. They don’t need to have special knowledge of financial systems. They may not speak the local language.
  • What are their goals? We can assume that it’s mostly about getting money, so we need to optimize our design for that. However, users may want to make a deposit, check their balance, or perhaps other things. Therefore, the process must be flexible.
  • What is the context? ATMs are typically out in the open. Particularly in busy thoroughfares, there is often a queue to use them. Privacy is important for people in order for them to feel that it’s secure. There may be glare on the screen during the day, or not enough light in the evening.

These considerations are just scratching the surface, but start to shed light on what this might mean for the solution.

Determining What Makes Something Usable

According to usability thought leader Jakob Nielsen, one of the “founding fathers” of usability, usable systems have five high-level qualities. These guide our thinking as we design, and become our frame of reference as we evaluate. Learn these key qualities and ask yourself the following questions to evaluate whether you’re on the right track to usability.

Learnability is making sure that people can begin to perform (at least) basic tasks with little effort. It’s critical to the initial use of a product or service.

  • What is the user’s required knowledge level coming into the site, app, product, or service?
  • What information have they been primed with?
  • Are there too many features?
  • Have conventions been used from other sites, apps, or systems that your audience is familiar with?
  • Did you provide a way to learn about the less obvious, secondary features?

Efficiency is about ensuring that people can achieve their goals quickly with the system — after they learn how to use it.

  • Does the system reduce hesitation with clear language and feedback?
  • Are there special shortcuts for power users?
  • Is technology leveraged to reduce user effort?
  • Least importantly, how many clicks (in a digital interface) does it take to use?

Memorability means ensuring that people can not only learn to use the system initially, but that they don’t have to relearn it with every use.

  • Does the system call out changes since the user’s last interaction?
  • Are the interface elements placed in conventional positions?
  • Would users be able to re-establish proficiency after not using it for a while?

Error management is critical to reducing the number, magnitude, and impact of any user errors.

  • Have the designers anticipated errors that users may make and try to prevent them?
  • Have designers  considered pre-emptive error management?
  • Is the system forgiving of users’ mistakes?
  • Are any error messages clear?

Satisfaction determines whether people continue to use the product/service.

  • Does the product/service do what it says it will do?
  • Is it different from others in its category?
  • Is it visually appealing?
  • Is it well executed from a technical perspective?
  • Are there pleasant surprises? Does it delight?

Usability Is Not Only a Digital Concern

The usability of your phone, or that ATM, depends just as much on the design of the hardware as the software. Usability is also critical to products with no digital interface at all, such as in the design of OXO kitchen utensils, where the company prides itself on giving people an easy and ergonomically sound way to open jars, peel fruit and veggies, and so on.

Conversely, think about how difficult some microwaves are to use, and because they’re all different, it’s difficult to go from using one to another. Finally, consider services, rather than physical or digital products. For instance, is the process for renewing your driver’s license a usable one? Think about the opportunities there.

“Usability” Is Not Enough

We’ve all experienced products and services that are technically “usable,” in that we can easily use it. However, we scratch our head and ask ourselves, “Why?” Usability is just one — albeit a very important — piece of the puzzle.

Peter Morville, the founding father of information architecture, got designers thinking more broadly when he published his now-famous “user experience honeycomb” diagram. The honeycomb serves as a reminder that, in addition to being usable, a product or service must be findable, accessible, useful, desirable, credible, and valuable. The diagram emphasizes the interrelationship among these attributes, as well as the fact that each is a lens into the success of the solution and can be individually evaluated and prioritized. Understanding all of this is where UX design comes into play.

Usability Honeycomb

Usability at General Assembly

Usability is at the core of everything UX design students learn at General Assembly, be it in our career-changing User Experience Design Immersive program, part-time on-campus or online courses, or design-focused short-form workshops and events. It’s baked into students’ work in researching users’ needs and goals, learning synthesis techniques to develop insights, and translating those insights into hypotheses and requirements.

Usability is reinforced both in students’ theory projects and work with real-world clients, in which they create early conceptual designs and wireframes, test them with users, iterate on the solution based on their learnings, and evolve the designs into final solutions. It’s at the heart of ensuring they understand the real problem before launching into the solution.

This kind of focus allows students to recognize the simple beauty in what Breville, the small-home-appliance company, did when it introduced a function on its toasters to brown bread just “a bit more.” That’s very much aligned with a person’s goal of getting that perfect breakfast. That’s what usability is all about.

Ask a Question About Our Design Programs

Meet Our Expert

Susan Wolfe, who teaches GA’s User Experience Design Immersive in San Francisco and Sydney, has practiced UX design, run consultancies, mentored project teams, and introduced UX design practices and cultures into organizations around the globe. She has established and managed in-house UX teams within software, hardware, and services companies in the Silicon Valley. In her work, she takes a holistic service design perspective and applies the most appropriate user-centered design thinking techniques to identify issues and ultimately create the optimal experience.

Susan Wolfe, User Experience Design Immersive Instructor, GA San Francisco and Sydney

Leave a Reply