Post on 03-Jan-2016
description
Ch 3 Interaction Design Process
Yonglei Tao
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Interaction Design An iterative process
through cycles of design-evaluation-redesign
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User-Centered Design (UCD) Pioneered by Donald Norman’s research
lab at UC San Diego A design framework for building usable
systems Principles Techniques
User-Centered Design (UCD) Design should emerge from the user’s
Tasks – data, functions, and workflows Goals Environment
Focus on human-centric issues Cognition Perception Physical attributes and conditions
Characteristics Early focus on users and their tasks Continuous evaluations to determine ease
of learning and ease of use Iterative design
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User-Centered Design Involving the following methods
User Participation Focus Groups Questionnaires Observations Walkthroughs Expert Evaluations Usability Testing
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Interaction Design Models Waterfall Model Spiral Model Dynamic Systems Development Method Prototype-Based Models Discount Usability Engineering Contextual Inquiry
Waterfall Model
A Modified Model
Discount Usability Engineering Proposed by Jakob Nielsen Basic ideas
Changes in user interface design are substantial in the early stages of development
No need to use comprehensive prototyping and usability testing techniques
Benefits derived from even small amounts of user testing would have a significant impact on the usability of the design
So “test early and often”
User Testing Problems that can be identified from a
usability test with n users can be described as follows
Basic Techniques Scenarios
Paper prototyping on the basis of scenarios Thinking aloud
Involve 3 to 6 users for usability testing Ask them to think out loud when performing
given tasks Collect data by note-taking
Heuristic evaluation Evaluate according to established usability
principles Involve a few reviewers to avoid personal bias Do early in the design process
Cost Savings in a Medium Project
Source - http://www.nngroup.com/articles/guerrilla-hci/
How Many Users in a Test? Test five users (Jakob Nielsen, 2012)
Allowing you to find almost as many usability problems as you would find using many more test users
Sufficient to collect insights to drive your design There are exceptions
Quantitative studies – test at least 20 users Card sorting – test at least 15 users Eyetracking – test 39 users for stable heatmaps
A small number of test users are more cost effective
More tests, not more users in each test
83 Case Studies by Norman Group
Source - http://www.nngroup.com/articles/how-many-test-users/