Introduction
Why is it important to consider product usability in a project? Which informatics professions make use of usability engineering ?
What are typical errors in completed design that did not take into account the principles of usability ? Comment, give an example from practise.
An interface design is based on the following principles:
Explain these issues and sketch related techniques and theoretical foundations.
Task
and user centered design
Task centered system design concerns with end-user perspective. Explain the phases: identification, requirements, design, walkthrough evaluation. State the goals of each phase and what techniques are suitable to achieve them.
How would you identify real users of a system and their tasks ? Discuss approaches when users and tasks already exist and when not (will arise in future)
What properties must have good task examples ? What facts are recorded and what is described ?
Characterize evaluation of design using walk-throughs. What is input for the walk-through, what properties are tested and evaluated ? Describe the process of evaluation.
Explain and argument the main differences between goal oriented design and task oriented design.
A goal centered design emphasizes the development of persona and defining of characters - roles of system users. What characteristics describe persona, how do we identify them ?
High
level models of human-computer interaction
Schneiderman model of interaction distinguishes semantic and syntactic knowledge. Which usability problems are related to syntactic knowledge ?
Schneiderman model of interaction distinguishes semantic and syntactic knowledge. Which usability problems are related to semantic knowledge of computer concepts and task concepts ? Characterize mapping problems.
In a simplified Norman model we consider 4 stages of interaction (intention, selection, execution, evaluation). Explain these stages and their interrelations when performing a task.
4-stages model identifies gulfs of execution and evaluation. Explain these issues.
4-stages model supports design solution by raising and considering questions on
visibility, quality of conceptual model, good mappings a high-quality feedback.
Explain, comment, give examples.
User
centered design
Explain the difference between system-centered and user-centered design.
What is participatory design, positives and negatives.
Methods for involving a user - customer. Explaining design, visualization, sketching and prototyping. Explain these techniques and their usage in early and late design stages.
Explain the following attributes of sketches in the design process: quick, timely, disposable, plentiful, clear vocabulary, constrained resolution, consistency with state, suggesting and exploring.
When designing we use prototypes with a constrained functionality (horizontal, vertical, scenarios). Explain differences and usage.
Evaluating
interfaces with users
Evaluating interfaces with users is applied in all stages of project lifecycle. What are the main goals in following stages: pre-design, initial design, iterative design, acceptance testing ?
What are differences between naturalistic and experimental approaches to evaluation ? Explain tradeoffs and external and internal validity of testing.
Evaluate pros and problems of experimental assesment of the real product usability . How can be the problems partially eliminated ?
Usability evaluation applies low cost methods, such as inspection, extracting the conceptual model, observation, query techniques and continuous evaluation. Characterize these techniques and discuss pros and cons.
For designing questionaries it is necessary to determine the goals, formulate questions, define set of responders and the way of carrying out. Questions may be opened or closed. Explain the issues, give examples.
Explain the basic ethic principles before testing: user's time, comfort, privacy, informing, volunteering.
Explain the basic ethic principles during testing: user's time, comfort, privacy.
Explain the basic ethic principles after testing: comfort, privacy, informing.
Controlled
experiment focuses on: hypothesis,
measurement, confidence, replicability, control of variables and conditions,
unbiased execution. Comment and explain the issues.
T-test
and null hypothesis. Significance level and errors of type 1 and 2.
Consequences for design decisions.
Four
scales of measurement are nominal, ordinal, interval, ratio. Explain briefly,
give examples and consider the possible sources of errors.
( NO Explain
correlation, regression and ANOVA. )
The
following concepts are important for designing:
perceived
affordances, causality, visible constraints, mapping, transfer effects, idioms &
population stereotypes, conceptual models, individual differences, difficulty
of design. Explain the selected concepts, provide positive and negative
examples.
Why is design hard ? Consider latest developments, influence of market, prices and specific problems related to the fact that "product" is implemented in a general-purpose computer.
Tufte formulated the following principles for data visualization: show the data, do not hide the message, avoid distortion, many in small space, large set make coherent, encourage comparison, overview and detail together, clear purpose. Comment these principles in a selected application (several screen snapshot).
Visual variable attributes are: position, size, shape, value, orientation, color, texture, motion. The attributes may be selective, associative, quantitative, order, length. Comment these characteristics for the selected attributes.
The snapshots of a given application contain visual variables with specific attributes. Mark these attributes and asses the characteristics they express.
What are interface metaphors, theirs purpose and possible problems ? Comment emotional coloring, possible restrictions, typical errors of metaphors' usage (overly literal, cute, mismatched).
Explain "interface with direct manipulation" and related issues visibility, reversible and incremental actions, pointing and moving, continuous display. Provide an example of direct manipulation interface and comment where, and in what form are these notions used.
Screen design can be guided by CRAP (contrast, repetition, alignment, proximity). What these principles enforce and guarantee ? Show their application on a given screen snapshot.
CRAP (contrast, repetition, alignment, proximity) may be supported by grids. Compare given screen snapshots and criticize the design using CRAP&grid principles.
What are KLM(
KeystrokeLevelModel) and GOMS (Goal, Operator, Method, Selection rule) models
used for ? Compare efforts and explain their usage in practise.
Describe
a general model of human processing of external information. Explain the
cooperation of perceptual, cognitive
and motor systems during interaction. Discuss how the parameters memory capacity, decay, representation and
processing cycle time influence interaction. Explain the model with a
given example.
Reaction
time is closely related to decision-making. What are the factors influencing
decision time ? Explain Hick-Hyman law of reaction time.
Usage of
Fitt's law in KLM evaluation.
Characterize
manipulation techniques according metaphor:
Exocentric
m. – WIM, automatic scaling
Egocentric
m. – Virtual hand (classical, GoGo,…)
– Virtual pointer (ray casting,
aperture, flash light, image plane)
What are
advantages and disadvantages of selected methods when used for closed and
distant manipulation ?
Metaphor
and techniques for way-finding in virtual environment.
For
evaluating interfaces various criteria may be used, such as following
heuristics:
Evaluate
a selected application given several screen snapshots.