Whether checking ratings of a restaurant on Zomato or chatting with a friend on Facebook messenger, how the users/customers interact with the app plays a very crucial role. Your user/customer should be able to perform the desired action on your mobile platform. If the user does not understand how to perform the task on the app, the probability of them using the app again drops drastically.
The limited screen size of the mobile form factor puts limitations on the number of features and content you can put on the screen. Hence the same design principles of the web interface design may not apply to your mobile interface design.
Usability evaluation helps you identify usability gaps in the existing designs and quantify the usability of interfaces.
According the ISO definition, usability is concerned with the “effectiveness, efficiency and satisfaction with which specified users achieve specified goals in particular environments”. It typically deals with understanding if the user will be able to complete the goal or not.
Some of the factors that affect mobile app usability are:
- Ease of learning and use,
- The help and problem solving capability provided,
- Emotional aspects and multimedia properties,
- Commands and minimal memory load,
- Control and efficiency,
- Typical mobile phone tasks.
With a large number of apps being developed, it is important to focus on usability of the app by use since it determines whether or not the app will used by the user.
The major usability characteristics involve:
Google and Apple have developed their specific user interface guidelines for Android and iOS apps. These guidelines put together all the characteristics which designers and developers should take into account during the application design and development process. These guidelines also help in conducting a usability evaluation.
Common methods of conducting mobile usability evaluations are:
- Laboratory experiments
- Field Studies
- Hands on experiment
Users don’t always do what they say they do with the product. So, it is necessary to observe the user. Usually these tests are performed in a closed environment with around 8 to 12 users, which represent your target audience. They’re asked to perform some predefined tasks. Then the time to complete the specified task, number and type of errors per task, number of users making a particular error etc are recorded.
The environment is controlled by isolating the users from all the conditions which are not relevant for the experiment. It helps in evaluating different designs of the interface of the app.
In this method, data is collected using interviews and observations. Normally, this data contains task flows, user needs and product requirements. Investigators generally keep notes while the user is using the app and keep asking questions. Unlike laboratory testing, in this method the user is exposed to real environment and the observations are made.
During the test, the users are asked about how they performed a specific task, about their goals and where they find difficulty.
Hands on experiment
Usability of the mobile app is measured quantitatively. The display load, clarity of operation possibilities, completeness of operation menu and display self-adjustment possibilities is checked.
Most product teams make assumptions about the user behavior while conceptualizing the product experience. Thus, it becomes important that these tests are performed during the design phase using click through prototypes. This helps save a lot of rework which is quite expensive in the later phase of the product life cycle.