# Usability Testing

> Watching real users attempt real tasks in a product or prototype to find where they struggle, hesitate, or fail.

- Category: Process & Methods
- Canonical: https://www.themasterly.com/glossary/usability-testing

Usability testing is deceptively simple: give a representative user a realistic task and watch, mostly in silence, where they get stuck. It works on anything a person can attempt something in, from a paper sketch to a live product, and it remains one of the highest-leverage methods available because problems repeat across participants.

Pairing it with a [heuristic evaluation](https://www.themasterly.com/glossary/heuristic-evaluation), an expert review against known usability principles, catches two different things: the problems users hit, and the ones they quietly tolerate without ever mentioning.

## How many people, and from which groups

Nielsen's rule of thumb puts five participants at around 85% of the usability problems in a design. The number gets quoted more often than the condition attached to it: the model assumes comparable users working in comparable ways.

B2B software rarely meets that condition. An admin configuring permissions, an analyst living in a dashboard and a finance approver signing off once a month are three populations, and five of the first tells you nothing about the other two. Nielsen's own guidance for that case is three to four participants per group, so a product with three roles needs closer to ten sessions than five.

Run small rounds often rather than one large study a year. Five sessions, a round of fixes, five more sessions finds more than fifteen sessions in a single week, because the second round tests the repairs.

## Moderated, unmoderated, and what each is for

| | Good for | Costs | Blind spot |
|---|---|---|---|
| **Moderated, live** | Early designs, complex flows, asking why | Scheduling and an hour per session | The moderator can lead the witness |
| **Unmoderated, recorded** | Volume, specific tasks, regression checks | Cheap per session | No follow-up questions when something surprising happens |
| **Guerrilla** | Fast reads on consumer-shaped flows | Almost nothing | Hard to do at all in B2B, where the user is a role |
| **Contextual, at their desk** | Understanding real conditions and workarounds | Travel, access, patience | Small samples and awkward logistics |

For B2B, the contextual version repays the trouble more than its cost suggests. Watching someone use the product with their real data, their real interruptions and the spreadsheet they keep alongside it explains behaviour that no lab session reproduces.

## Running the session

**Write the task as a goal.** "Upgrade your plan and add a teammate" leaves the route to the participant. Naming the menu items tests nothing.

**Stay quiet.** The urge to help is strong and it destroys the data. When somebody stalls, wait. If they cannot proceed unaided, you have the finding.

**Ask what they expected, not what they think.** "What did you expect to happen there?" produces information. "Do you like this?" produces politeness.

**Watch the pauses.** People rarely say a label confused them. They stop, reread it, then guess. The pause is the signal, and it disappears from any summary that only records success or failure.

**Record the task, not the impression.** Whether they finished, how long it took, where they hesitated, what they said while hesitating. Impressions gathered at the end are heavily influenced by whether the session went well.

## The recruiting problem in B2B

The method is cheap. The participants are not, and this is where B2B teams give up.

You cannot intercept enterprise admins in a coffee shop, and the people you can reach easily are the friendliest customers, which biases the sample toward people already succeeding. Three routes work in practice: ask customer success for accounts matching a specific behaviour rather than a general willingness, recruit from users who recently churned or downgraded, and test with internal staff who share the workflow but not the product knowledge, such as support agents, while remembering they are a proxy and not a user.

Whatever the route, screen for behaviour instead of demographics. "Someone who has invited a teammate in the last month" produces a more useful session than "a product manager at a mid-sized company".

## What it finds, and what it cannot

Usability testing finds confusion, wrong assumptions, invisible controls, misread labels and the exact point where a flow breaks down. It answers *why*.

It does not tell you how often the problem occurs across your whole user base, whether people would pay, or which of two acceptable designs performs better at scale. Those need analytics, pricing research and [A/B testing](https://www.themasterly.com/glossary/ab-testing) respectively. A finding from five people is a hypothesis about the population, and the honest way to report it is as a described failure rather than a percentage.

## Turning sessions into decisions

The sessions are the easy part. Most of the value leaks out afterwards, in the gap between what was observed and what the team does about it.

**Sort by severity, not by order of appearance.** A problem that stops a task cold outranks one that slows it down, which outranks one participant's dislike of a word. Without that sort, the notes become a flat list and the flat list becomes a backlog nobody prioritises.

**Separate what happened from what you think it means.** "Two participants clicked the plan name expecting selection" is an observation. "The cards need a radio button" is a proposal, and somebody may have a better one. Mixing the two makes the observation arguable, which is the one thing it should not be.

**Show the clip.** Thirty seconds of a customer failing settles a debate that a summary cannot. It also removes the suspicion that the researcher chose findings to fit an existing view.

**Write down what you decided not to fix.** Sessions surface more than any team can address. Recording the ones you are consciously leaving stops them being rediscovered every round as if they were new, which is what a [research repository](https://www.themasterly.com/glossary/research-repository) is for. Where a round produces more observations than a list can hold, [affinity mapping](https://www.themasterly.com/glossary/affinity-mapping) is the usual way through them.

## In practice

Five participants, one task: upgrade your plan and add a teammate.

Three of the five stall on the same screen. The plan picker reads as informational rather than clickable, because the cards have no affordance suggesting they can be selected. Nobody on the team had ever seen this happen, for the reason teams never do: they all knew where to click.

The fix takes an afternoon. The more valuable part of the session is what the participants said while stuck, which was not "this is confusing" but "I thought I had already chosen". That sentence points at a different fix from the one the team would have made from a drop-off number alone, which would have been to redesign the page.

## Where teams get it wrong

- **Testing colleagues.** Anyone who knows the product cannot be surprised by it.
- **Reading the route aloud.** A task containing the steps measures whether the participant can follow instructions.
- **Rescuing people.** Every intervention deletes the finding you were there for.
- **One round, once.** Testing before launch and never again turns the method into a formality.
- **Counting instead of describing.** "Three of five failed" is not a result on its own. What they were trying to do when they failed is.
- **Testing only the happy path.** Give somebody an empty account, or one with far too much data in it, and the product behaves differently.

## Related terms

- [User Research](https://www.themasterly.com/glossary/user-research)
- [Prototyping](https://www.themasterly.com/glossary/prototyping)
- [Heuristic Evaluation](https://www.themasterly.com/glossary/heuristic-evaluation)
- [UX Audit](https://www.themasterly.com/glossary/ux-audit)

## Learn more

- [UX Audit service](https://www.themasterly.com/services/ux-audit)

## FAQ

**How many participants do you need for a usability test?**

Five per distinct user group. Jakob Nielsen's model puts five participants at roughly 85% of the usability problems in a design, on the assumption that the participants use the product in similar ways. B2B products with admins, members and approvers have three groups, so three to four from each is closer to right than five in total.

**Should usability tests be moderated or unmoderated?**

Moderated when you need to ask why, which covers early designs and complex flows. Unmoderated when you need speed and volume on one specific task. Most teams start moderated and add unmoderated checks later for flows they have already studied.

**What is the difference between usability testing and A/B testing?**

Usability testing tells you why something fails, from a handful of people. A/B testing tells you which version wins, from a lot of them. One explains, the other measures, and on low-traffic B2B products the explaining method is usually the only one with enough data to work.

**Can you run usability testing on a live product?**

Yes, and on a prototype, a wireframe or a competitor's product. Anything a person can attempt a task in will do. Testing a competitor is an underused version, because you learn what your prospects already find normal.

**What makes a good usability test task?**

A goal with no instructions inside it. "Add a teammate to your plan" is a task; "click Settings, then Members, then Invite" is a script that guarantees success. The task should describe what the person wants, never the route.

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