Design and Evaluation of Iterative Systems n For most interactive systems, the ‘design it right first’ approach is not useful. n The 3 basic steps in the development of an user-centered, iterative system are -- Design, Evaluation and Implementation. n A good design takes into account characteristics of the intended users and the work they do.

n Principles, guidelines or methodologies are used for a good design n Principles are collection of statements that advise the designer how to proceed. n Guidelines are collection of tests that can be applied to an interface to determine if it is satisfactory. They are more specific and quantitative. n Methodologies are formalized procedures that guide the structure of effective design when followed in sequence. Discipline of Design

Evaluating systems and their user-interfaces n Evaluation of existing practice often precedes design and evaluation of prototypes and systems is used throughout the processes of design, implementation and deployment.

Research and Evaluation strategies n Field strategies-- field studies and field experiments n Experimental strategies-- experimental simulations and laboratory experiments n Respondent strategies -- judgement studies and sample surveys n Theoretical strategies-- formal theory and computer simulations

Five Approaches to Interface Evaluation n Heuristic evaluation with usability guidelines n Cognitive walkthrough n Usability testing n Usability engineering n Controlled experiments

Heuristic evaluation with usability guideline n Guidelines can be vague and contradictory such as the “be consistent” guideline. n Huge sets of guidelines are difficult to evaluate. Therefore, a small set of very general design guidelines or heuristics are used for evaluation.

Cognitive walkthroughs n A set of representative tasks is selected and stepped through keystroke by keystroke, menu selection by menu selection. n Idea is to evaluate design for ease of learning. n But low level focus on keystrokes often left high level problems unrecognized. Also time demands was a problem,that was later solved by cognitive jogthrough. n Pluralistic walkthroughs and Inspection and design reviews are other methods.

Usability Testing n It involves experimental tasks that reflect important or frequent uses of the system, which should be selected through contact with real users and work situations, not by intuition. n Evaluator may change the task or even the interface when a major error is encountered. n Thinking aloud, co-discovery techniques are used.

Usability Engineering n It is user testing that is more formal i.e quantitative performance goals called metrics are set by the interface specialists or the developers. n E.g new users must be able to create ad save a file in their first 10 minutes with the system.

Controlled experiments n Advantage- study if individual behavior n Disadvantage- use of the interface is very different in a work setting as compared to in a laboratory. n Issue to be considered is whether to select a ‘ within subject design’ or a ‘between subject design’

How to design usable systems n Components of Usability--- System reliability and responsiveness System functions Reading materials Language Translation Installation Support -Group Users Field maintenance and service

Usability Design Process- The Four Principles n Early and Continual Focus on Users-- understanding behavioral, attitudinal characteristics of users and their jobs n Early and Continual User Testing-- users do real work on prototype and their performance and reactions are measured n Iterative Design-- system is modified based on results of user testing n Integrated Design-- all aspects of usability evolve in parallel and under one focus

Usability Design Phases n Gearing up Phase : It is an information gathering and conceptualization phase n Initial design Phase: Involves a preliminary specification. Information about users and their work is collected. n Iterative Development Phase: with behavioral goals and user feedback, modification is achieved. n System Installation Phase: involves installing the system in the customer’s location, introducing it to the users and employing training materials.

Methods for. Early and continual Focus on Users n Talk with users-- direct contact, interview n Visit customer location n Observe the users working n Videotape n Learn about Work Organization n Try it Yourself n Thinking aloud n Participative design n Task analysis n Testable Behavioral Target Goals

Methods for early and continual User Testing n Printed or Video scenarios n Early user manuals n Mock ups n Simulations n Early prototyping n Early Demonstrations n Thinking Aloud n Hallway and Storefront methodology n Try to Destroy It contests n Bulletin Boards, Conferencing, forums

Methods to Carry out Iterative Design n For iterative design we need to identify required changes, have an ability to make changes and a willingness to make changes. n Software tools (UIMS) n A checklist

Integrated Design n It requires that one group at the very beginning, be given sufficient resources to drive control usability and to invent what is needed to make usability good. n It requires a departure from the fractional development practices where various aspects of usability are developed in different loosely related departments, divisions, cities and companies. n Checklist can be used to achieve the same.