Human-Computer Interaction & Usability Engineering

Guidelines and Standards

Standards And Guidelines

When designing software, it would be helpful if we could reach out for the “HCI cookbook” and follow a recipe for success. Unfortunately, no such book exists. The study of usability engineering is still in its infancy so there are no proven rules which tell you what to do. There are, however, guidelines and standards emerging which can be of immense value to designers. Learn by others’ mistakes and/or successes.

Example:
Apple Macs came with software which was embraced by home users world-wide. The windows application was soon emulated (and improved upon?) by other software companies.

Designers developing systems should always have a good reference book and a set of design standards. When it comes to evaluating that system, conformity with standards and guidelines should be high on the list of priorities.

Standards

Before the Industrial Revolution, tools tended to be tailored to their users. However, mass production meant that more uniform designs were needed. This led to formal design standards becoming increasingly popular. Standards promote both safety and efficiency and enable us to progress more easily.

Example:
An everyday clock is standardised and many other things are defined from standard. I.e. they are referred to as “clockwise” or “anti-clockwise”. There is no logical reason why we can’t tell the time on a backward clock, it’s just that the standard clock makes life much easier.

Advantages And Disadvantages Of Standardisation
The main advantage of standardisation is, as mentioned before, that it makes using anything easier to use if you’ve used it before. You only have to learn how to use it once, subsequent use of items with the same standards is enhanced by the familiarity gained. This is good for both frequent and occasional users. Standardisation works well when followed efficiently.
The main disadvantage of standardisation is that it can restrict innovation.

Example:
The QWERTY keyboard standard is very precise in terms of layout, size of keys and pressure needed. (Note however there are a number of standards for function key layout). This has meant that new keyboard designs (e.g. Dvorak) are not accepted even though test may show it is a far more efficient arrangement of keys. Increasing incidence of repetitive strain injuries however have led to more ergonomic designs but they are still based on the QWERTY layout standard.

Another disadvantage is that it makes differentiation more difficult. Also, for those trying to establish standards, it may be hard to get agreement and it has to be timed properly. Early enough to save work being repeated, but late enough to incorporate improvements and technological advances.

Computer Standardisation
From a user’s point of view, the design of computers still leaves a lot to be desired. The technology is still immature and it is now time to get formal standards in place. Informal standards have, however, crept in.

Example:
Windows - opening, closing, re-sizing, title and menu bars, scroll bars, etc.

Software is restricted by our understanding of the human mind, hardware is limited by technology. Software standards are therefore more difficult to establish that hardware standards. Computer software has the additional design feature that it can be flexible for the user. I.e. users can customise the screen. This tailoring can either benefit the user or cause confusion by introducing inconsistencies.

Where To Find Usability Standards
The subject of standards in Human Computer Interaction is currently at the centre of much debate. Standards for principles of dialogue design, usability characteristics and usability assurance are currently being developed by the International Standards Organisation (see Preece, p56). The ISO are also developing guidelines for specific types of dialogue and user assistance.

Guidelines
(see Newman and Lamming p373 - 382)

Guidelines come from past experience of problems encountered. For system designers, guidelines provide us with advice on how to tackle design problems and suggest solutions to the problems. Designers continually come across unfamiliar design issues.

Example:
It may be that you are designing a system to support novel functionality, or that you want to try a new design approach on a familiar activity.

When designers find themselves in unfamiliar design territory, help can be sought from guidelines which have been derived from other peoples’ experience and research. There are far more guidelines to turn to than there are standards.

Advantages Of Guidelines
Guidelines are useful for enhancing the design process and, in particular, may introduce a concept new to the designer which can be used in the design or kept for a future design.

Example:
Guideline - use a second dialogue window to get the user to confirm an action.

Guidelines are also good for helping the designer make better design choices or decide on a design strategy.

Example:
Guideline - locate the command line near the bottom of the screen unless it is clear the user’s gaze will be elsewhere.

Another advantage of guidelines is that they can be used in the evaluation process, perhaps as a checklist for testing the usability of a design.

Disadvantages Of Guidelines
Disadvantages of guidelines tend to be related to how we use them, or rather that we forget their limitations. Many are contradictory and it can be difficult for the designer to select the best guideline for the task in hand. It’s tempting to select the one which is easiest to apply. Applying the guideline can also be difficult since guidelines tend to be written in as few words as possible. Sometimes the true message of the guideline is missed. A further disadvantage is that you may want to apply several guidelines to one problem. In which order do you apply them? Conflict can arise because guidelines can be based on vastly different theories and experiences, or because a guideline is limited in its scope.

Where To Find Usability Guidelines
Guidelines can be found in professional, trade and academic journal articles. This is the best way to get information about current practice and experience. Other good sources are guides issued by software companies and books on the subject of software design (see Preece p53). Below are some useful guidelines.

Guidelines For Screen Displays
· only show data which is essential to making a decision or performing an action
· show all data needed for the current task, do not force memory for data on other screens
· do not ask for data which the software already knows
Guidelines From Typography For Form Design
· make them pleasing to the eye and uncluttered
· provide aids to scanning and browsing
· choose appropriate groupings, tabular layout and typeface
· ensure there is consistency within the system, between systems and between systems and paper
Guidelines For Messages
· make sure they are clear, concise and courteous, and the sentence style should be present tense
· they should contain what is needed to continue i.e. what to do and when to do it
· be as specific as possible, giving what is directly and immediately useful
· decide on whether they are to be abbreviated or detailed, be guided by the users’ requirements or requests
· allow them to stay on the screen (and be visible) until they are acted upon and then automatically cleared
Guidelines For Error Messages
· give a clear indication of type
· say why it has occurred
· tell user what to do about it - try to interpret the error, suggest alternatives and allow the user to edit the command, not re-key it
· don’t scare the users with inappropriate language (fatal error) and tell the user the truth!
· Don’t antagonise the use - avoid negative words (illegal) and don’t be pedantic (only one space character)
· give confirmatory messages, it’s good to reward the user rather than chastise all the time

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