1 Error Messages Displays Interface Evaluation

2 Error Messages for the Product Be as specific and precise as possible. Be constructive: indicate what needs to be done. Use a positive tone: avoid condemnation. Choose user-centered phrasing Consider multiple levels of messages Keep consistent grammatical form, terminology, and abbreviations. Keep consistent visual format and placement.

3 Attaining Good Error Messages Establish a message quality-control group. Include messages in the design phase. Place all messages in a file. Review messages during development. Attempt to eliminate the need for messages. Carry out acceptance tests. Collect frequency data for each message. Review and revise messages over time.

4 Colour Guidelines - Benefits Soothes or strikes the eye Accents an uninteresting display Facilitates subtle discriminations in complex displays Emphasizes the logical organization of information Draws attention to warnings Evokes emotional reactions of joy, excitement, fear, or anger.

5 Colour Guidelines Use colour conservatively: limit the number and amount of colours. Recognize the power of colour to speed or slow tasks. Ensure colour coding supports the task. Have colour coding appear with minimal user effort. Place colour coding under user control. Design for monochrome first. Use colour to help in formatting.

6 Colour Guidelines - Guidelines Be consistent in colour coding. Be alert to common expectations about colour coding. Use colour changes to indicate status changes. Use colour in graphic displays for greater information density.

7 Colour Guidelines - Dangers Resolution may degrade with colour displays. Colour pairings may cause problems. Colour fidelity may degrade on other hardware. Printing or conversion to other media may be a problem.

8 RED is the most dominant of all colours. It tends to raise blood pressure, pulse rate and even your temperature… an excellent environment for creation. Seeing Red? Feeling Blue? "Colour can affect your mood and even your metabolism, according to various studies." YELLOW is a high visibility colour said to have a favourable effect on human metabolism. It tends to appear brighter then white. When children are asked to draw a happy picture, they most often draw it in yellow. WHITE is the perfectly balanced colour, clear and natural in its influence. White instantly suggests goodness and purity.

9 Seeing Red? Feeling Blue? Cont. VIOLET is the colour of luxury and sensuality. Violet creates an unusual atmosphere - unexpected and lavish. GREEN represents a withdrawal from stimulus. Greens and blue-greens tend to reduce nervous and muscular tension. BLUE has qualities opposite to red. It can lower blood pressure and pulse rate.

10 The Energy of Colour “An entire field has been developed surrounding the psychology of color in marketing. For instance, fast food restaurants are decorated with vivid reds and oranges, encouraging diners to eat quickly and leave. Bright primary colors are used for toys, books and children’s web sites because young children prefer them and respond more positively than to pastels or muted colors.” “In North American mainstream culture, the following colors are associated with certain qualities or emotions:”

11 The Energy of Colour. Red – excitement, strength, sex, passion, speed, danger Blue – (listed as the most popular color) trust, reliability, belonging, coolness Yellow – warmth, sunshine, cheer, happiness Orange – playfulness, warmth, vibrant Green – nature, fresh, cool, growth, abundance Purple – royal, spirituality, dignity Pink – soft, sweet, nurture, security White – pure, virginal, clean, youthful, mild Black – sophistication, elegant, seductive, mystery Gold – prestige, expensive Silver – prestige, cold, scientific

12 Why Evaluate Understand how products/users behave in the real world –Does the design meet the users needs? Compare Designs Engineer towards a goal –Iteratively improving the design Check conformance to a standard. –Is it up to snuff

13 Types of Evaluation Observing and Monitoring (passive) –Cameras –Personal observation –Collecting keystroke (task) data. Collecting User's Opinions –Interviews –Surveys Experimentation and Benchmarking –Quantitative analysis of data –Very scientific approach Hypothesis testing Controlling variables

14 Types of Evaluation Cont. Interpretive Evaluation –Informal way of collecting data Users Products –Natural setting –Attempts to extract info from findings of evaluation –No formal guidelines for users, product –No goals are set for the evaluation. –A look and see what happens kind of approach.

15 Types of Evaluation Cont. Predictive Evaluation –Predict how users will behave without testing the product on users. –Evaluator uses… Inspection Simulation Expert Reviewing Task Analysis –… to predict problems with users –Usually involves a low-level prototype or mock-up