CX Insights

The ABC of Usability – Part 8

3 min read

A return to a series that has seen some neglect of late: The ABC of Usability.

To those unfamiliar, we will aim to add new terms to our existing glossary of Usability and User Experience definitions; terms we deem useful, interesting or – hopefully – a mixture of the two!

Here we begin with five new Usability terms and their definitions:

Pareto Principle or 80/20 Rule

This harks back to Italian economist Vilfredo Pareto, who in 1906 observed that 80% of the land in Italy was owned by 20% of the population; developing the principle through observing that 20% of the pea pods in his garden contained 80% of the peas.

Though this sounds like crazy reasoning, it is used as a common rule of thumb in business and can also be applied to Usability: Users will use 20% of your product’s features, 80% of the time; and thus as a designer, the majority of your design efforts (80%) should be spent on the most important 20% of the product.

This principle, interestingly, has some mathematical foundation; roughly followed by a power law distribution – known as Pareto distribution.


A UX design practice where real world objects are represented digitally, creating visual metaphors. A basic example are radio buttons; taken from their namesake. These mimic the buttons on old analog radios, where when selecting one preset channel, the other buttons would pop out.

Skeuomorphs are particularly important in User Interface design, as they provide the user with objects they are familiar with in the real world – increasing familiarity within a system. Further examples include sliders (metaphor for analog sliders), software-based calendars (designed to appear as paper-based calendars) and tablet gestures (turning the pages of a book).

Apple, under Steve Jobs, was a particular proponent of this digital design technique.


Heuristic Evaluation

Created by Danish usability consultant Jakob Nielsen, this involves check-marking an interface against a predefined set of ‘Heuristics’; criteria which the interface must meet. The interface is judged by one or more reviewers, and is provided with a score for each heuristic – based on their estimated impact on user performance or acceptance; the results identifying any problems within the interface.

The simplicity and low cost of this evaluation method offer its main advantage, being extremely effective in budget and time restrictive situations, the only major downside being that it may require personnel with a certain level of knowledge and experience in order to be effective.

Source: UX Centered Blog

Fitts’s Law

An empirical (based on observation, rather than pure theory) model of human movement, used to predict the time required for a user to point at an object on the screen of the computer with a pointing device, ie. mouse. Popular within the design of GUI’s, the importance of this model has risen in recent years with the prevalence of this interface form.

The model takes into account factors such as distance from the object and the object’s size to calculate how easily and efficiently a user can select it. This can be important when designing call for actions: increasing conversion rates on web pages for example.

First being formulated in 1954, it is becoming increasingly relevant today with the rise of touchscreen devices.

Source: Six Revisions

Paper Prototyping

A throwaway prototyping method; wherein the designer can quickly sketch, test, then resketch ideas on paper.

The low cost and speed of this technique allows rapid evolutions to be made within the prototype, reducing the costs and annoyance associated with problems occurring later in the design process. Users/testers often feel more open to express their feelings about a system at this stage due to the interface not having a polished look and appearing largely in as a draft.

Source: 1stwebdesigner

Oliver McGough
Passionate UX Designer and Marketer.