Are usability and functionality linked? The short answer is yes. After all, without functionality you won’t have usability!
From a dynamic testing perspective, you will probably want to test the functionality and have confidence in that before you hand it over for usability testing. So how do you separate them?
With usability, you’re focusing on attributes that are specific to this area, such as satisfaction, efficiency and effectiveness. You’re making sure that the scenarios you're giving your users, and the questions that you're going to ask them, are guiding them towards giving you that information.
It is a fine path that isn’t always clear-cut. But what it boils down to is what you're going to ask your users - and what they might possibly say - about your system, which will then help you to come up with the best assessment of usability.
Can usability testing be carried out after a system has gone live? It certainly can, as long as it is not the first time you are testing the usability. Otherwise, you’ll encounter many of the same issues you would when releasing freshly written software into production without testing.
Having said that, in the real world you have a wider range of users whose experiences you can draw upon, since they'll be using your product in a wider range of circumstances. Thus, it can be beneficial to get that type of unique insight from users.
The way you normally extract that type of information is through some form of survey. You can use standardised surveys to get these insights from users, or produce your own to get the specialised feedback that you’re really after.
The System Usability Scale (SUS) is a quick and reliable way used by many to measure usability. It consists of ten standardised questions with five response option, from strongly agree to strongly disagree, and a SUS score above 68 tends be considered above average while anything below is below average.
Context of the feedback
While it always beneficial to get some sort of average of the ratings you collect during usability testing, you do have to think a bit deeper about the meaning of the numbers. To that end, you may need to do some more statistical analysis.
Anyone who knows their numbers will know that they can be deceiving. So a small amount of statistical analysis can help you understand the information you have gathered.
One area to be mindful of is the spread of answers. By taking an average you run the risk of hiding the spread. You might have quite a wide range of divergent views, which will have different implications for usability compared to a result where everyone's score is centred around the same area.
You also need to think about the extreme answers that may skew your averages. For example, you might have a grumpy business user who didn't really want the system but everyone's forced him to have it, so he may end up complaining about it regardless of its functionality and usability.
Empower the user
Delivering great usability and functionality is critical for your app to succeed in today’s market place, however it is not an easy thing to do.
You can learn how to effectively test for usability with our popular ISTQB Usability Tester Certificate course. If you need help delivering the digital experience that your customers expect, contact us to find out how we can transform your applications to deliver the quality your customers demand.