Week 8 - The process of interaction design Prof. Ahmed Sameh

Overview What is involved in Interaction Design? Some practical issues Importance of involving users Degrees of user involvement What is a user-centered approach? Four basic activities Some practical issues Who are the users? What are ‘needs’? Where do alternatives come from? How do you choose among alternatives? A simple lifecycle model for Interaction Design Lifecycle models from software engineering Lifecycle models from HCI

What is involved in Interaction Design? It is a process: a goal-directed problem solving activity informed by intended use, target domain, materials, cost, and feasibility a creative activity a decision-making activity to balance trade-offs It is a representation: a plan for development a set of alternatives and successive elaborations

Importance of involving users Expectation management Realistic expectations No surprises, no disappointments Timely training Communication, but no hype Ownership Make the users active stakeholders More likely to forgive or accept problems Can make a big difference to acceptance and success of product

Degrees of user involvement Member of the design team Full time: constant input, but lose touch with users Part time: patchy input, and very stressful Short term: inconsistent across project life Long term: consistent, but lose touch with users Newsletters and other dissemination devices Reach wider selection of users Need communication both ways Combination of these approaches

What is a user-centered approach? User-centered approach is based on: Early focus on users and tasks: directly studying cognitive, behavioral, anthropomorphic & attitudinal characteristics Empirical measurement: users’ reactions and performance to scenarios, manuals, simulations & prototypes are observed, recorded and analysed Iterative design: when problems are found in user testing, fix them and carry out more tests

Four basic activities There are four basic activities in Interaction Design: 1. Identifying needs and establishing requirements 2. Developing alternative designs 3. Building interactive versions of the designs 4. Evaluating designs

Some practical issues Who are the users? What are ‘needs’? Where do alternatives come from? How do you choose among alternatives?

Who are the users/stakeholders? Not as obvious as you think: those who interact directly with the product those who manage direct users those who receive output from the product those who make the purchasing decision those who use competitor’s products Three categories of user (Eason, 1987): primary: frequent hands-on secondary: occasional or via someone else tertiary: affected by its introduction, or will influence its purchase

Who are the stakeholders?

What are the users’ capabilities? Humans vary in many dimensions: size of hands may affect the size and positioning of input buttons motor abilities may affect the suitability of certain input and output devices height if designing a physical kiosk strength - a child’s toy requires little strength to operate, but greater strength to change batteries disabilities(e.g. sight, hearing, dexterity)

What are ‘needs’? Users rarely know what is possible Users can’t tell you what they ‘need’ to help them achieve their goals Instead, look at existing tasks: their context what information do they require? who collaborates to achieve the task? why is the task achieved the way it is? Envisioned tasks: can be rooted in existing behaviour can be described as future scenarios

What do we need to look out for in interface design issues?

Where do alternatives come from? Humans stick to what they know works But considering alternatives is important to ‘break out of the box’ Designers are trained to consider alternatives, software people generally are not How do you generate alternatives? ‘Flair and creativity’: research and synthesis Seek inspiration: look at similar products or look at very different products

How do you choose among alternatives? Evaluation with users or with peers, e.g. prototypes Technical feasibility: some not possible Quality thresholds: Usability goals lead to usability criteria set early on and check regularly safety: how safe? utility: which functions are superfluous? effectiveness: appropriate support? task coverage, information available efficiency: performance measurements

Testing prototypes to choose among alternatives

HCI in the software process Software engineering and the design process for interactive systems Usability engineering Iterative design and prototyping Design rationale

Lifecycle models Show how activities are related to each other Lifecycle models are: management tools simplified versions of reality Many lifecycle models exist, for example: from software engineering: waterfall, spiral, JAD/RAD, Microsoft, agile from HCI: Star, usability engineering

The waterfall model Requirements specification Architectural design Detailed design Coding and unit testing Integration and testing Operation and maintenance

Activities in the life cycle Requirements specification designer and customer try capture what the system is expected to provide can be expressed in natural language or more precise languages, such as a task analysis would provide Architectural design high-level description of how the system will provide the services required factor system into major components of the system and how they are interrelated needs to satisfy both functional and nonfunctional requirements Detailed design refinement of architectural components and interrelations to identify modules to be implemented separately the refinement is governed by the nonfunctional requirements

DSDM lifecycle model

The Star lifecycle model Suggested by Hartson and Hix (1989) Important features: Evaluation at the center of activities No particular ordering of activities; development may start in any one Derived from empirical studies of interface designers

The Star Model (Hartson and Hix, 1989) UCD is a very general philosphy that instantiates itself in the context of a design project. Within HCI there have been many attempts to come up with actual life cycles where users are central. Examples include Rubinstein and Hersch successive iteration of 5 stages, info collecion, design, implementation, evaluation and deploment. The one here is taken fromHartson and Hix model came about by analysing how design takes place in practice evaluation is central: results of each ativity are evaluated before going onto next one both bottom-up and top -down required in waves software designers are familiar with this in their work and call it ‘yo-yoing’ it is important to do both structure and detail at the same time in practice this is what is done - but the end result suggests otherwise corporate requirments dictate a top=down approach which is wha gets recorded ch 5 of Developing User Interfaces (An Overview of Systems Analysis and Design) p- nice step-by-step methodology for doing user-centred design

Usability engineering lifecycle model Reported by Deborah Mayhew Important features: Holistic view of usability engineering Provides links to software engineering approaches, e.g. OOSE Stages of identifying requirements, designing, evaluating, prototyping Can be scaled down for small projects Uses a style guide to capture a set of usability goals

ISO 13407

Verification and validation Real-world requirements and constraints The formality gap Verification designing the product right  Validation designing the right product   The formality gap validation will always rely to some extent on subjective means of proof Management and contractual issues design in commercial and legal contexts

The life cycle for interactive systems cannot assume a linear sequence of activities as in the waterfall model lots of feedback! Requirements specification Architectural design Detailed design Coding and unit testing Integration and testing Operation and maintenance

Usability engineering The ultimate test of usability based on measurement of user experience Usability engineering demands that specific usability measures be made explicit as requirements Usability specification usability attribute/principle measuring concept measuring method now level/ worst case/ planned level/ best case Problems usability specification requires level of detail that may not be possible early in design satisfying a usability specification does not necessarily satisfy usability

part of a usability specification for a VCR Attribute: Backward recoverability Measuring concept: Undo an erroneous programming sequence Measuring method: Number of explicit user actions to undo current program Now level: No current product allows such an undo Worst case: As many actions as it takes to program-in mistake Planned level: A maximum of two explicit user actions Best case: One explicit cancel action

ISO usability standard 9241 adopts traditional usability categories: effectiveness can you achieve what you want to? efficiency can you do it without wasting effort? satisfaction do you enjoy the process?

some metrics from ISO 9241 Usability Effectiveness Efficiency Satisfaction objective measures measures measures Suitability Percentage of Time to Rating scale for the task goals achieved complete a task for satisfaction Appropriate for Number of power Relative efficiency Rating scale for trained users features used compared with satisfaction with an expert user power features Learnability Percentage of Time to learn Rating scale for functions learned criterion ease of learning Error tolerance Percentage of Time spent on Rating scale for errors corrected correcting errors error handling successfully

Iterative design and prototyping Iterative design overcomes inherent problems of incomplete requirements Prototypes simulate or animate some features of intended system different types of prototypes throw-away incremental evolutionary Management issues time planning non-functional features contracts

Techniques for prototyping Storyboards need not be computer-based can be animated Limited functionality simulations some part of system functionality provided by designers tools like HyperCard are common for these Wizard of Oz technique Warning about iterative design design inertia – early bad decisions stay bad diagnosing real usability problems in prototypes…. …. and not just the symptoms

Design rationale Design rationale is information that explains why a computer system is the way it is. Benefits of design rationale communication throughout life cycle reuse of design knowledge across products enforces design discipline presents arguments for design trade-offs organizes potentially large design space capturing contextual information

Design rationale (cont’d) Types of DR: Process-oriented preserves order of deliberation and decision-making Structure-oriented emphasizes post hoc structuring of considered design alternatives Two examples: Issue-based information system (IBIS) Design space analysis

Issue-based information system (IBIS) basis for much of design rationale research process-oriented main elements: issues – hierarchical structure with one ‘root’ issue positions – potential resolutions of an issue arguments – modify the relationship between positions and issues gIBIS is a graphical version

structure of gIBIS Sub-issue Issue Position Argument supports responds to objects to supports questions generalizes specializes

Design space analysis structure-oriented QOC – hierarchical structure: questions (and sub-questions) – represent major issues of a design options – provide alternative solutions to the question criteria – the means to assess the options in order to make a choice DRL – similar to QOC with a larger language and more formal semantics

the QOC notation Criterion Option Question Option Criterion Option … Consequent Question … Question

Psychological design rationale to support task-artefact cycle in which user tasks are affected by the systems they use aims to make explicit consequences of design for users designers identify tasks system will support scenarios are suggested to test task users are observed on system psychological claims of system made explicit negative aspects of design can be used to improve next iteration of design

A simple interaction design model Exemplifies a user-centered design approach

Summary Four basic activities in the design process Identify needs and establish requirements Design potential solutions ((re)-design) Choose between alternatives (evaluate) Build the artefact User-centered design rests on three principles Early focus on users and tasks Empirical measurement using quantifiable & measurable usability criteria Iterative design Lifecycle models show how these are related

Summary The software engineering life cycle Usability engineering distinct activities and the consequences for interactive system design Usability engineering making usability measurements explicit as requirements Iterative design and prototyping limited functionality simulations and animations Design rationale recording design knowledge process vs. structure