Learnability, Flexibility and Robustness

Academic researchers say a user-oriented system design, which pays attention to capabilities and will contribute to better human and computer interaction. So in the mid 80’s the term Human Computer Interaction (HCI) was introduced.
Technological advances lead to the importance of effectiveness, efficiency and other conveniences. Nowadays almost all software or applications are competing to make their products more attractive both in terms of appearance and benefits so that users will also be interested in using these products.
In designing the interface (Design User Interface) a system must pay attention to several theories, paradigm principles and user models in design. Interactive systems must be used to increase application success. System interface design is an important thing that must be done before creating an interface, one of the important factors in IMK is Usability, the components that affect Usability include:
1. Learnability
Learnability is a convenience that can be learned by users at all levels, especially new users to use the system effectively and achieve the most optimal performance.
The principle of learnability is needed effectively to achieve maximum performance, including:
· How easily the user can learn a system
· How fast someone can understand and master until they become proficient.
· What is the ability of a person to maintain the knowledge that has been obtained after a certain period of time.
Principles That Affect Learnability, namely:
Predictability: The user interface can be predicted what can be done by it. As an example of a menu that is named in accordance with its function so that users can predict the possibility of what happens if the menu is accessed. Example: in the Ms. program. Word is available icons that represent several commands by looking at the picture only, then the user will know its use, for example when going to print a soft copy document into a hard copy just choose the Printer icon and follow the next step.

Synthesizability is support from the user to feel the benefits of the old system that has been used with the new system that is being used. This principle can help the user to estimate the effect of the processes carried out previously in the current state. Examples such as moving files.

Familiarity is the ability of a user interface to be more easily recognized by its functions and capabilities by the user. Examples of almost all software or applications use icons like the image below:

(Minimize, Restore Down / Maximize, Close), that’s because icons like that are common and easier for users to understand.

Generalization, this generalization principle can help users to increase knowledge of specific interactions inside or outside the application. Examples such as the operation of cut & paste in different applications.
Consistency is the similarity of behavior between similar tasks / operations / situations but in different ways. Users are usually more comfortable with something familiar, easy, and has mastered it.

2. Flexibility
Flexibility is the ability to do a task in various ways. flexibility (variations in ways / models for users and systems to exchange information.
The principle of flexibility has various explanations below:
a. Dialog Initiative
It does not complicate the user by placing a limit and how the dialog can be carried out. Can be divided into 2 namely user pre-emptive and system pre-emptive. A pre-emptive user is a user who starts the action first. While the pre-emptive system is a system that does everything first.
b. Multithreading
Allows the user (user) to do more than one task at the same time. Furthermore, this type is divided into 2 namely concurrent and interleaved. The concurrent type performs many tasks simultaneously, while the interleaved type includes many tasks one at a time.
c. Task Migratability
Task migratability is the ability to move a task’s performance to an entity that can do it better.
d. Subtitutivity
Allow the user (user) to choose a method of interaction that suits him.
e. Customizability
The ability of the user to modify the user interface by the user (adaptability) and by the system (adaptivity).

3. Robustness
Robustness is the ability of the UI (user interface) to carry out recovery which is the level of support provided so that the user can determine the success or goals to be achieved. The main purpose of this principle is to support users in determining the success and objectives of the assessment.
Robustness is divided into several categories, namely:
a. Observability
Is the user able to explain the internal state of the system from what he understands?
b. Browsability
Explore the current state without changing it.
c. Reachability
Explore through circumstances that might be observable.
d. Persistence
How long have the observed conditions persisted?
e. Recoverability
the ability to take corrective actions to recognize mistakes.
f. Responsiveness
User perception of the amount of communication made with the system.
g. Task Conformance
Does the system support all the various desires of the user to carry out the task in the way expected.
According to Mandel (1994) Usability problems that commonly occur include:
Bad visualization
Information that can be read is damaged
Components that can not be understood
Annoying interlude
Confusing navigation
Inefficient navigation
Inefficient operation
Excessive or inefficient scrolling
Information overload or too much
Inconsistent design
Information that is not updated

A good system design is able to provide user satisfaction with the system, providing benefits perceived by the user of the system both in the short or long term use.