1. Usability Guideline (development version)
Date Created: 2/2/15 – 2/25/15 (tentative)
Description
Usability is concerned with the user experience in term of users’ needs, satisfaction, their
abilities as well as limitations. Surprising system actions, tedious sequences of data entries,
difficulty in obtaining necessary information, etc. can create barriers for users and result in
dissatisfaction
1. Cognitive load (human memory limitation) – The system/interfaces should try to
minimize human cognitive limitation by reducing short-term memory load and recalling.
 Provide a method to keep track of users’ navigation (i.e. breadcrumb site
navigation, etc.)
 Avoid using popup message, especially application-modal (application cannot be
used till popup is dismissed) and system-modal (system cannot be used till popup
is dismissed)
 Provide mechanism that takes the users back to the site they came from
 Do not require users to remember information from pages to pages
 Important instructions (i.e. form field format) should remain on the screen while
needed.
 Reduce the requirement for human calculation (automate difficult tasks)
 Interactive elements (i.e. buttons, links) should show that they have been activated
2. Simplicity and goal-oriented – The system/interfaces should not provide unnecessary
complexity to the users. It should also provide a simple method for users to accomplish
their goal.
 Site navigation structure should be simple with clear conceptual model
 Avoid providing distracting information
 Avoiding banner blindness design (design that looks like advertising)
 Avoid providing ambiguous prompts such as “An error has occurred”.
 Step-by-step instructions/guides to complete application/form should be provided
 Provided instructions should be clear, goal-oriented and noticeable.
 Category, labels should reflect its content accurately
 Elements should be designed using Gestalt’s principles as possible:
o Closure: People tends to perceive objects as a whole
o Proximity: People often perceive objects that are closed together as a
group
o Similarity:People often perceive similar objects as a group
o Symmetry: People tends to perceive objects as being symmetrical
o Continuity:People often perceive objects in a continuous form rather than
disconnected segment
o Figure/Background: People tends to separate visual fields into
foregrounds and backgrounds

2. o Common Fate: People often perceive objects that move together as a
group
 Fitts’ Law (the more distance decreases or target grows, the less the decrease in
pointing) should be followed:
o Navigation menu should be broad and shallow rather than deep
o Interactive elements (i.e. buttons, links, etc.) should be large enough for
users.
o Clickable region should be as large as the actual interactive elements
3. Consistency – Related elements should be presented in a similar way so that it does not
create difficulties for users.
 Identical terminology should be used
 Visual presentation such as visual cues should be consistent throughout the site
 Information displayed and data entered by users should be the same.
 Keyboard consistency (Same function should be assigned to same keyboard
shortcut within the same application/page)
4. Responsiveness – The system/interfaces should inform the users about the status of the
system as well as any tasks that are performed by the users.
 During site loading, display important information first (i.e. during loading,
display whole image with low resolution first rather than half of the image with
high resolution)
 Page should load quickly, usually from 1-5 sec. More than 5 seconds, users can
think the system does not work.
 Provide immediate feedbacks to the users for any delays occurred.
5. Error tolerance, prevention and recovery – The system should prevent the users from
making errors. In addition, it should be able to detect errors and present it in a way that
the users can fix it.
 Provide simple error handling system
 User confirmation is required before changes are made
 Confirmation page or information should be clear and accurate
 Warning/ error message should contain clear information with explanation of the
problem.
 Ensure that users’ progress is not lost by users mistake (or machinery issue)
 Provide a method for users to undo their actions
6. Flexibility, predictability and efficiency – The system/interfaces’ features can be
adjusted to the needs of the users to reduce unnecessary interactions. In addition, the
system/interfaces should not provide surprising and hideous actions. It should behave in
response to the users’ actions.
 Allow the use of shortcuts, hotkeys, and accelerators.
 The design can be customized according to users’ needs.
 Allow users to control the pace of the interaction

3.  Objects that trigger an action should not be automatic (i.e. Prevent auto-
submission form)
 System’s features should be easy to use without any assistance
 Users are able to know the sequences followed by the performed actions or
features.
Sources:
 Jakob Nielsen 10 Usability Heuristics guidelines
 Shneiderman’s Eight Golden rules of Interface Design
 Weinschenk and Barker usability guideline.
 25-point Website Usability Checklist
 Designing with the mind in mind, 2nd edition
 100 Things Every Designer Needs To Know About People