Usable Software - By Design

The design quality of an application is one of the most important factor that convinces visitors to complete orders. The quality of a design is based on certain universal principles that need to be followed. The use of well- established principles increases the probability that a design will be successful. Moreover, these principles can be used as a means of checking the quality of our design process and product.

In todays world where everyone is pressed for time, one of the main principles on which design should be based is Accessibility. The principle of accessibility asserts that design should be usable by people of diverse abilities, without special adaptation or modification. It is also known as barrier free design and universal design. Accessible designs are based on perceptibility, operability, simplicity, and forgiveness. Forgiveness is achieved when designs minimize the occurrence and consequences of errors.

Aesthetics play an important role in the way a design is used. Aesthetic designs look easier to use and have a higher probability of being used, whether or not they are actually easier to use. Studies reveal that aesthetic designs are more effective at fostering positive attitudes. We should always aspire to create aesthetic designs that is designs responsive to or appreciative of what is pleasurable to the senses.

A sense of unity and cohesion contributes to the designs overall aesthetic and perceived stability. This is not to overlook the fact that there maybe exceptions when elements are misaligned to attract attention. Elements in text and graphics can be minimized to allow viewers to participate in the completion of the pattern. It reduces complexity and increases the interest aspect in the design.

A good design is based on the principle of Consistency. Consistency enables people to efficiently transfer knowledge to new context, learn new things quickly, and focus attention on the relevant aspect of a task.

Constraints in design help to simplify usability and minimize errors. For example, dimming or hiding options that are not available at a particular time effectively constraints the options that can be selected. This reduces the probability of error.

Good design follows the hierarchy of needs principle. The principle specifies that a design must serve the low-level needs (e.g., it must function), before the higher level needs such as creativity, can begin to be addressed. The five key levels are: functionality, reliability, usability, proficiency, and finally creativity. Creativity is the level in the hierarchy where all needs have been satisfied, and people begin interacting with the design in innovative ways. Designs at this level are perceived to be of the highest value.

Quality design does not occur without iteration. This makes room for ample use of prototypes, which allow designers to improve their understanding of design requirements. However, we should plan for and employ design iteration. This means we must establish a clear criteria defining the degree to which design requirements must be satisfied for the design to be complete.

Simplicity should be preferred to complexity in designs. Unnecessary elements decrease a designs efficiency.

The designs that help people to perform optimally are often not the same as the designs that people find most desirable. The balance between performance and preference must be taken into careful consideration in the development of the design requirements. One of the ways to bring about this balance is to determine accurately the relative importance of each, and/or observe people interacting with the design or a similar design in real contexts.

The needs of a product change over the course of its life cycle. It is important to understand the dynamic of these changes in order to focus and design resources accordingly. All products progress sequentially through four stages of existence: introduction, growth, maturity, and decline. It is important to note that the development cycle for the next generation product begins during the growth stage of a current-generation product.