Interface Evaluation Models and techniques GOMS analysis Keystroke Level Model Cognitive dimensions of notation Hierarchy of design principles Task analysis Layout appropriateness PIE model

Interface Evaluation (2) Measurements Time Counts Geometry Satisfaction

Layout Measures Assume widgets w 1, w 2, …, w n Examples where n = 1? n = 2? Assume tasks T 1, T 2, …, T k where the tasks are represented as sequences of widget interactions Assume task frequencies f 1, f 2, …, f k Where should the widgets be placed?

Example – Information Overlay Virtual tour of the Sistine Chapel – With information overlay With information overlay Button placement? Explaining GUEP?

User Experience (UX) Extracted from a presentation by Ira Blossom User Experience describes how a person feels when interacting with a system Focus on UX of web sites. Or is it websites? Capture overall reaction and response to details – Previously discussed web-based forms – Global layout: One or two sidebars One or two top bars

UX (2) Users hate (how do we know?) – Horizontal scrolling – Multi-colored text – Hard-to-read font due to design or size – Bad search engines – Advertisements, especially the in-line version – Confusing instructions

UX (3) Users appreciate: – For logins in an environment where there are many potential options, specify what information is needed address used as the UserID Previously defined UserID User codes – Not having to make choices when Consequences are unknown No confirmation of results is provided

More Appreciation – Consistent use of words Avoid using synonyms in a different places for the same action. E.g. Submit/Send – Instructions or help pages or instructional videos for sites that provide services

Contrasting Sites The Houdini Museum Steamtown Lackawanna Coal Mine Tour Electric City Trolley Museum

Popular Sites Note differences in design: dare.com Yahoo Craig's List Pepsi YouTube

Musike Scoring System Developed for menu-based systems Modified for web pages Works well in complex environments Provides weighted sum of scores of individual factors Each individual factor to be based on a measurable design principle

Example -- AWSP Application of Web Site Principles Evaluates web sites Based on Jakob Nielsen’s design principles Rewritten by Lea Taylor Case Study