Usability Introduction Andrew Wadsworth guest lecture for LIS

Usability Introduction Andrew Wadsworth guest lecture for LIS 390 -W 1 A

Design Ø the act of working out the form of something Ø an arrangement scheme Ø something intended as a guide for making something else Ø a preliminary sketch indicating the plan for something

Design… as a process Ø The approach that engineering (and some other) disciplines use to specify how to create or do something. A successful design must satisfies a (perhaps informal) functional specification (do what it was designed to do); conforms to the limitations of the target medium (it is possible to implement); meets implicit or explicit requirements on performance and resource usage

Interface Ø a common boundary between two things Ø a program that controls a display for the user (usually on a computer monitor) and that allows the user to interact with the system Ø A boundary across which two systems communicate.

User Interface Ø a program that controls a display for the user (usually on a computer monitor) and that allows the user to interact with the system Ø The aspects of a computer system or program which can be seen (or heard or otherwise perceived) by the human user, and the commands and mechanisms the user uses to control its operation and input data.

Usability Ø The effectiveness, efficiency, and satisfaction with which users can achieve tasks in a particular environment of a product. High usability means a system is: easy to learn and remember; efficient, visually pleasing and fun to use; and quick to recover from errors.

Human-Computer Interaction Ø (HCI) The study of how humans interact with computers, and how to design computer systems that are easy, quick and productive for humans to use.

System Acceptability Ø Practical Acceptability o Cost o Compatibility o Reliability o Usefulness Ø Social Acceptability

Usefulness Ø Utility Ø Usability o Easy to learn o Efficient to use o Easy to remember o Few Errors o Pleasing to use

Components of Usability Ø Learnability Ø Efficiency Ø Memorability Ø Errors Ø Satisfaction

Learnability Ø Characteristics o easiest component to measure o some systems take zero time to learn Ø Measurement o time to complete a task successfully o a set of tasks in a minimum period of time Ø Considerations o most users don’t take the time to completely learn the system before they begin to use it

Efficiency of Use Ø Characteristics o refers to when a user’s level of performance no longer increases over time (levels out) o users may never reach the steady-state performance level (always increasing) o most users plateau once they have learned “enough” Ø Measurement o must have access to experienced users o at steady-state level where performance no longer increases Ø Considerations o must determine expertise level for the system to get a representative sample of users

Memorability Ø Characteristics o casual users only intermittent user of a system, but are familiar with it o they don’t need to learn from scratch o improvements in learnability often make a interface easy to remember o not tested as much as other components

Memorability Ø Measurement o casual users away from the system for a period of time, then measure the time it takes to complete tasks o after an initial user test, ask users questions about the system and have them explain the effect of commands or the name of the command Ø Considerations o casual users typically apply to utility software

Errors – Few or Catastrophic Ø Characteristics o we want to get low error rates for users o an error is any action that does not accomplish the desired goal towards the completion of a task

Errors – Few or Catastrophic Ø Measurement o count the number of incorrect actions made by users while performing a task o incorrect actions may only slow a user o some errors effect time only and thus relate to efficiency o catastrophic errors, not discovered by the user, lead to bad results or incompletion of the task Ø Considerations o separate simple errors from catastrophic errors

Satisfaction (subjective) Ø Characteristics o how pleasant it is to use the system o subjective and biased o there are many ways to measure Ø Measurement o ask the user about their experience – usually via short questionnaire at the end of test o collect objective data and extract subjective preferences of the user o EEG’s, pupil dilation, heart rate, etc.

Satisfaction (subjective) Ø Considerations o Attitudes toward computers can impact attitudes towards a systems usability o For some systems it’s more important to be enjoyable to the user rather than fast to learn and use (ie, games)

Accelerators Ø Are interface elements that allow users to perform frequent tasks quickly Ø Most useful as users gain expertise with the system

Novice into Experts Ø A novice who is performing highly and begins to switch over and use accelerators may experience a temporary performance dip

Usability Considerations Ø User Testing Ø User’s individual characteristics and differences o Must consider both when testing usability o “know thy user”, try to classify them

Other Usability Considerations Ø show shortcuts with menu items to assist users and promote accelerators Ø online help with examples and links for further research Ø short menus (for novice users), long menus (for expert users)

Concluding Thoughts Ø previous experience with similar interfaces really helps using and learning other systems Ø more knowledge in the specific domain will greatly effect a users ability to know what a system is all about Ø users are not designers, simply providing only custom interfaces based on the users preference doesn’t work well

Simple Usability Testing Ø In a usability test, one user at a time is shown a Web site (prototype, screen shots, print-outs) and asked to: o Figure out what it is o Try to use it to do a typical task or set of tasks

Usability Testing Truisms Ø 1. "There is no such thing as a bad usability test. " Ø 2. One test is better than none. Ø 3. Test early, test often. Ø 4. 5 users will uncover 85% of usability problems. Ø 5. Shoe-string usability testing is still usability testing.

Usability Testing Ø What to test o "Get it"- purpose, value, how it's organized, how it works o Task - ask the user to do something and observe

Usability Testing Ø How to test o Determine the specific tasks and parts of the site you will be testing. Carefully think through your instructions (don't reveal answers with your questions). Write out a script.

Usability Testing Ø How to test o Test your test. Try it yourself. o "We are testing the site, not you. " o Encourage users to think out loud. Ask them again. o Questions. Answer questions with questions not explanations. o Keep instructions simple. o Ask more questions. o Report what you saw.

Usability Testing Ø Test Summary o Review what you learned. o Figure out what needs to be fixed and how to fix it. o Usability testing will give a wealth of data, the trick is determining what to act on. o Focus on specific issues, tweak before redesigning.

Usability Testing Ø Test Summary o The most common issues you encounter will be users that are: • "unclear on the concept“ • labels that don't mean what you intended • too much or too little information accompanying your content and interactions o Resist adding "features" and make sure you tackle the "big stuff".

Types of Usability Tests Ø Exploratory Test Ø Assessment Test Ø Validation Test Ø Comparison Test