I won’t go through all of them in detail but hopefully, I can give you a snapshot of what each one does and how you can use them.
A. Exploratory user testing format
This is where you interview and/or observe participants at the place (context) that your product or service would be used most. Interviewing in context can trigger participants’ memories when recounting their journey. This means that what they recount can be much closer to reality than what users “think” they do outside of their context/environment.
By observing your users in this setting, you’re also able to marry up what they say to the actions they take. This is great for forming user journeys.
These studies normally take more than a session for participants to complete as they happen over a period of time. Participants would go about their day to day business but take notes also known as “diary entries” when they perform certain tasks that you set. It’s great for documenting the various touch points users have when interacting with your product/service.
This is one of the cheapest to run by interviewing participants in your own office or over the phone. It can be used for a variety of purposes across your project workflow from initial Discovery through to Development. More often than not, we combine this with another testing format by asking some questions in the first half of the testing session followed by something interactive in the second half. E.g. user interview followed by card sorting exercise.
B. Evaluative user testing format
You’ve probably heard of this one as it’s the most common user testing format and is also the one we are concentrating on in this guide. You can test from early concepts and sketches all the way through to well-established products that need improving.
We’ve found the key to running usability tests is not to find everything that is wrong with a product, but rather to give you a direction or the next step to improving it.
On top of that, a lot of issues that come up may not be as much of an issue as you thought because people have a tolerance level and can tolerate some smaller issues that don’t need to be fixed right now. Steve Krug author of Don’t Make Me Think has a great example, describing what he calls the Reservoir of Goodwill. This is where everyone who enters your site has a cup filled with motivation (or Goodwill) to find the information they’re looking for. Some things may reduce their motivation, some things may refill it. Sometimes a critical usability issue can cause the cup to drop instantly to zero. It’s these critical usability issues we want to find and fix first, that are the highest priority to then test again and find the next issue.
When it comes to usability testing, we recommend testing as frequently as possible. Preferably every time you iterate or revise a solution.
Nielsen Norman Group who is one of the leaders in UX says that you only need to test with 5 participants.
From this graph*, you can see a plateau after 5 people, making it less cost-effective to continue testing with new participants. Instead, test as frequently as you can, knowing you can find the most critical usability issues with 5 participants.
Card sort tests
Mostly used for testing navigation when it comes to labelling and categorising.
If you want to know which designs or solutions are giving you the best conversion rates, A/B testing can help. This is especially the case if it’s more cost effective to make small changes on an already established product that has a good amount of traffic.
Keep in mind that depending on traffic volume, it can take a while for your tests to reach statistical significance.
* Reference: https://www.nngroup.com/articles/why-you-only-need-to-test-with-5-users/