Usability tests are manual tests used to check that the user interface is understandable. The focus of the tests are to ensure that product meets its intended purpose. These sort of tests can be subjective and are usually impossible to automate. It is important to differentiate usability testing from simply showing an interface to someone and asking them “Do you understand how this?”. It is usually done by creating a scenario such as “Can you find and add this song to a new playlist” and observing the steps that the user takes to perform the task.
Usability tests can be valuable for a variety of reasons. For online applications and sales if a website is difficult to use or the product hard to find the user will leave. Remember your biggest enemy in these cases is the back button. For all software made to be used usable software will improve productivity. This can be especially important in your sales pitch or when trying to move to a new process internally.
Keep in mind before performing any usability testing that there are 5 components relating to quality you should keep in mind.
Learnability. How easy is it for users to accomplish basic tasks the first time they encounter the interface?
Efficiency. Once users have learned the interface, how quickly can they perform tasks?
Memorability. When users return to the interface after a period of not using it, how easily can they re-establish proficiency?
Errors. How many errors do users make, how severe are these errors, and how easily can they recover from the errors?
Satisfaction. How pleasant is it to use the design?
One of the quickest ways to perform usability testing is to select random individuals and ask them to use the product of service. This is also known as hallway testing since this can include asking people passing by in the hallway. This can be a very effective method to finding serious problems for some software. Of course this is probably not the most effective way to test specialist software such as ultrasound controllers, but for anything consumer facing it can be an effective technique. Generally you can convince people to do this sort of testing for free or for very low cost if you are polite about it.
Expert reviews are another form of usability testing which can overcome issues with hallway usability testing. It is where experts in a given field are asked to evaluate a product. Generally the following 10 usability heuristics by Nielson are used (taken from wikipedia)
Visibility of system status. The system should always keep users informed about what is going on, through appropriate feedback within reasonable time.
Match between system and the real world. The system should speak the user’s language, with words, phrases and concepts familiar to the user, rather than system-oriented terms. Follow real-world conventions, making information appear in a natural and logical order.
User control and freedom. Users often choose system functions by mistake and will need a clearly marked “emergency exit” to leave the unwanted state without having to go through an extended dialogue. Support undo and redo.
Consistency and standards. Users should not have to wonder whether different words, situations, or actions mean the same thing. Follow platform conventions.
Error prevention. Even better than good error messages is a careful design which prevents a problem from occurring in the first place. Either eliminate error-prone conditions or check for them and present users with a confirmation option before they commit to the action.
Recognition rather than recall. Minimise the user’s memory load by making objects, actions, and options visible. The user should not have to remember information from one part of the dialogue to another. Instructions for use of the system should be visible or easily retrievable whenever appropriate.
Flexibility and efficiency of use. Shortcuts unknown by the novice user—may often speed up the interaction for the expert user such that the system can cater to both inexperienced and experienced users. Allow users to tailor frequent actions.
Aesthetic and minimalist design. Dialogues should not contain information which is irrelevant or rarely needed. Every extra unit of information in a dialogue competes with the relevant units of information and diminishes their relative visibility.
Help users recognise, diagnose, and recover from errors. Error messages should be expressed in plain language (no codes), precisely indicate the problem, and constructively suggest a solution.
Help and documentation. Even though it is better if the system can be used without documentation, it may be necessary to provide help and documentation. Any such information should be easy to search, focused on the user’s task, list concrete steps to be carried out, and not be too large.
Of course this is a far more formal method of usability testing. Usually it will result in paying the testers for their time, however some professionals will be happy to do so without cost if you are able to make things convenient for them. Tools such as goto-meeting can help with this.