Organising and running a successful usability test starts with having a well-defined purpose for what you are testing.

Why should I define a purpose for a usability test?

Because a defined purpose in place helps you and your team to focus on what’s important. Agree on what success looks like so that you are all on the same page and know the direction to take.

Image about the diagram from the problem to solution when defining a purpose on usability test, explained on the next paragraph.

As you can see, in the Discovery and Defining stages of the first diamond above, having a more exploratory purpose is more suitable for understanding the problem and identifying opportunities. When we hit the Develop and Deliver phases in the second diamond, focussing on a more evaluative purpose is better.

Typically you would start projects with an exploratory purpose to identify the problems to solve. Next, you’d evaluate your solutions constantly when developing the solutions with low fidelity mockups and prototypes through to fully developed interfaces.

Let’s take a look at an example. Let’s say you are offering an online coffee subscription service.

There are numerous things you might want to test to improve your offering:

  • Why would people buy into an online coffee subscription?
  • How do people try/buy coffee currently?
  • Who tries/buys coffee on a regular basis?
Exploratory / generative - Advantages: Good for identifying opportunities. Allows you to see what users value as important or what their priorities are. Understand the context and environment that users will use your product in. Disadvantages: A broader purpose can often be looser and less defined. Hard to see short-term impact.


Exploratory purpose example:

At the moment we have multiple ideas that could be used to define a purpose for testing. In this case, we will focus on “Why would people buy into an online coffee subscription?”

We’d like to identify:

  • Who interacts with coffee and enjoys it regularly?
  • Where do people interact with coffee?
  • When do people interact with coffee?
  • How do people interact with coffee?

Why do people enjoy coffee?

The purpose of identifying these aspects is to focus on what problem needs solving or opportunity that can be taken advantage of.

Evaluative purpose example:

Let’s imagine we’ve completed the first diamond and decided to build the coffee subscription sign up process.

We’d like to identify in the sign-up process:

  • What are the critical roadblocks and pain points that are stopping people from signing up?
  • Was the sign-up process easy to understand?
  • How long did it take for users to complete the signup process? Now that we have that worked out, we can define some assumptions regarding the sign-up process that can be directly tested.

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