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Usability definition: As defined in ISO 9241-11 |
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The extent to which a product can be used by specified users to achieve specified goals with effectiveness, efficiency and satisfaction in a specified context of use
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Parameters of usability |
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Effectiveness : Task Completion |
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Efficiency : Lesser time / clicks |
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Satisfaction : Pleasurable activity |
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Benefits of Usability |
| Benefits to Users |
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- User satisfaction à User Delight
- More ease of use
- Efficiency increases
- Shorter learning cycle
- User perceived quality improved
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| Benefits to Developers |
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- User oriented thinking = Reduction in rework
- Designing for the users and not (only) Clients
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| Benefits to business |
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- Product quality improvement
- More value delivered à Priced higher
- Increased Profitability
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| Why Usability is important |
| Other sources report : |
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“There are about 43 million Web sites, and no one knows which ones are usable. The best sites we’ve found are usable only 42 percent of the time, and none that we have studied are usable a majority of the time ….”
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| Forrester Research : |
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Losing approximately 50% of the potential sales from a site as people can’t find what they need
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Losing repeat visits from 40% of the users who do not return to a site when their first visit resulted in a negative experience
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| Jacob Nielsen : |
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“Studies of user behavior on the Web find a low tolerance for difficult designs or slow sites. People don’t want to wait. And they don’t want to learn how to use a home page. There’s no such thing as a training class or a manual for a Web site. People have to be able to grasp the functioning of the site immediately after scanning the home page — for a few seconds at most.”
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Usability Engineering Goals |
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1. Compatibility (with the user) – Computer speaking my language
2. Learn ability – I can do that.
3. User friendliness – Easily
4. Effectiveness A – Accomplish user goals.
5. Effectiveness B – Business goals fulfilled.
6. Efficiency – faster.
7. User Satisfaction – Alright ! it was smooth !
8. User Delight – Wow I did not expect this.
9. Flexibility – good ! You could do it this way also, (Ctrl C Ctrl V)
10. Excellent User Experience. |
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Usability Engineering Definition |
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An Evidence based methodology that involves end users throughout the development process to product information systems that are measurably easier to use, learn and remember.
— By Jean Fox, Janice R. Nall.
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Understand the users |
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1. Who are the users of this specific product?
2. What are their User specific & Use specific needs?
3. What are the users goals for using this product?
4. Which areas are critical for meeting the user goals efficiently?
5. What other products they have used?
6. What is the terminology they use?
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Model of stages of use |
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Model for Stages of Use (for a particular application)
1. Novice
2. Advanced Beginner
3. Competent Performer
4. Expert
“User and Task Analysis for Interface Design” by Joann T.
Hackos, Janice C. Redish |
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GUI Design Process |
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1. Understand the Users
2. User goals, Business goals
3. User specific and use specific tasks
4. Define features
5. Design the work flow
6. Design the information structure
7. Design the front end |
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Usability Methods |
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Card Sorting
Technique that allows users to group the information on your Web site and helps to ensure that the site structure matches the way users think. |
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Contextual Interviews
Method that enables you to observe users in their natural environment to better understand the way users work. |
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Focus Groups
Moderated discussion with a group of users that allows you to learn about users’ attitudes, ideas, and desires. |
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Heuristic Evaluation
Usability inspection method where a group of usability experts evaluate the Web site against a list of established heuristics (or guidelines). |
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Individual Interviews
One-on-one discussions with users that allow you to learn how a particular user works and enables you to probe on a user’s attitudes, desires and experiences. |
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Parallel Design
Technique where multiple designers create mock-ups of the user interface and the best aspects of each design are used in the final design. |
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Personas
A fictional person that represents one of the major user groups for the site. The design team considers the needs of this fictional person when developing the site. |
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Prototyping
Draft model (or mock-up) of the Web site that allows the design team to explore ideas before fully implementing them. A prototype can range from a paper mock-up to interactive html pages. |
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Surveys (Online)
Series of questions asked to multiple users of the Web site that helps you learn about the people who visit your site. |
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Task Analysis
Method that involves learning about users’ goals – what they want to do on your Web site – and understanding the tasks that users will perform on your site. |
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Usability Testing
One-on-one sessions where a “real-life” user performs tasks on the Web site in order to identify user frustrations and problems with the site. |
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Use Cases
Description of how users will use a particular feature of the Web site. Use cases provide a very detailed look at how users interact with the site including the steps a user will take to accomplish each task. |
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Writing for the Web
Guidelines for optimizing content on the Web based on the way users read online. Involves chunking content, using bulleted lists, and putting the most important information at the top of the page. |
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Heuristic guidelines for usability testing |
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1) System Status shown
(Keep the user informed about what the computer is doing)
Providing feedback to the users
Appropriate method of feedback to be used |
2) Match with the real World
Use simple and natural dialog. Tell only what is necessary, and tell it in a natural and logical order. Ask only what the user can answer.
Speak Users language
Use metaphors familiar to users
Use words and concepts familiar in their work.
No computer jargon. |
3) User has to feel he is in command
Provide clearly marked exits so users can escape from unintended situations
User should be able to leave an unwanted state
Users should not get locked in the system |
4) Consistency in terminology and required actions.
Consistency in communication
Names, Images
Use sequence, Use of Controls
Behavior of controls |
5) Error prevention
Prevent errors from occurring by keeping choices and actions simple
UI should prevent an error from occurring
Minimize error situations |
6) Error Recovery
Give good, clear, specific and constructive error messages in plain text, no beeps and codes
Error messages should
Clearly indicate the problem
Constructively help users solve the problem
Be polite and express in plain simple language |
7) Recognition not recall
Minimize the user’s memory load
Objects and screens should be
Easily visible
Easy to interpret
User should not be forced to remember any information |
8) Flexibility
Provide shortcuts for frequent actions and advanced users
Provide multiple ways to accomplish the same task
If possible provide freedom to customize the system |
9) Minimalist Design
“Less is More”
Offer only relevant information and functions
Make invisible all the irrelevant information & functions
Seek minimum inputs from the users |
10) Help and Documentation
(Provide clear and concise, online help, instructions and documentation. Orient them to the users task)
Anticipate where users will require help
Provide appropriate help |
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