Copyright © 2008 Pearson Education, Inc. Publishing as Pearson Addison-Wesley Lecturer – Prof Jim Warren Lecture 4 - Usability Testing Based on Heim, Chapter 8

Copyright © 2008 Pearson Education, Inc. Publishing as Pearson Addison-Wesley Overview of the Usability Testing Module Lecture 4 (today) –Define usability –Focus on rationale, characteristics and process for doing usability tests Lecture 5 –Theory of usability test design and analysis of test results –Also cover questionnaire design and experiments for groupware Lecture 6 –Issues in experimenting on humans Lecture 7 –Some valuable kinds of usability tests, esp. light-and-easy methods (‘discount’ usability testing) 1-2

Copyright © 2008 Pearson Education, Inc. Publishing as Pearson Addison-Wesley 1-3 Chapter 8 Usability Testing What is Usability? What is Usability Testing? Design the Test Prepare for the Test Perform the Test Process the Data

Copyright © 2008 Pearson Education, Inc. Publishing as Pearson Addison-Wesley 1-4 What is Usability? Usability is the measure of the quality of a user’s experience when interacting with a product or system. (Usability.gov, 2006) Usability is a quality attribute that assesses how easy user interfaces are to use. (Nielsen, 2003) The extent to which a product can be used by specified users to achieve specified goals with effectiveness, efficiency and satisfaction in a specified context of use. (ISO standard , 1998)

Copyright © 2008 Pearson Education, Inc. Publishing as Pearson Addison-Wesley 1-5 What is Usability? Measures of Usability 1.Ease of learning—How fast can a user learn to accomplish basic tasks? 2.Efficiency of use—How fast can an experienced user accomplish tasks? 3.Memorability—Can a user remember enough to use it effectively the next time? 4.Error frequency and severity—How often do users make errors, how serious are these errors, and how do users recover from these errors? 5.Subjective satisfaction—How much does the user like using the system?

Copyright © 2008 Pearson Education, Inc. Publishing as Pearson Addison-Wesley 1-6 What is Usability? Qualitative or quantitative? –All of the usability measures can be assessed quantitatively How many errors per unit time; mean observed time to accomplish a task (efficiency) Even satisfaction can be quantified in terms of user responses to question (esp. Likert Scale, e.g. 5-point, questions – better than Yes/No) –But we are also interested in qualitative data about these things E.g. Asking just what the user does or does not like; or understanding the situations in which errors occur

Copyright © 2008 Pearson Education, Inc. Publishing as Pearson Addison-Wesley 1-7 What is Usability Testing? A usability test is a structured process used to explore the interaction between an objective participant and a proposed design Paper and pencil (paper prototype) –Heuristic evaluation –Cognitive walkthrough Usability Lab (functional prototype) –Formal testing with subjects

Copyright © 2008 Pearson Education, Inc. Publishing as Pearson Addison-Wesley 1-8 What is Usability Testing? Attributes common to most usability tests: –The goal is to improve a product. –Participants are real users. –The participants do real tasks. –Participants are formally observed. –The data are analyzed. –Recommendations for improvement are made. Dumas and Redish (1999)

Copyright © 2008 Pearson Education, Inc. Publishing as Pearson Addison-Wesley 1-9 What is Usability Testing? A usability test has three basic components: –Participants—Actual users who are asked to perform realistic and representative tasks using a proposed design –Design—May be a fully functioning prototype or a simple paper prototype –Tester—There might be only one tester or there might be a testing team

Copyright © 2008 Pearson Education, Inc. Publishing as Pearson Addison-Wesley 1-10 What is Usability Testing? Constraints on Usability Testing –Time Design Prepare Administer (an hour to an hour and a half) Analyze the results –Finance Equipment and software Laboratory time Recording media Participant compensation Refreshments

Copyright © 2008 Pearson Education, Inc. Publishing as Pearson Addison-Wesley 1-11 What is Usability Testing? Constraints on Usability Testing –Personnel—Formal usability tests require at least four people. –Laboratory—To perform a formal usability test, a dedicated laboratory is required.

Copyright © 2008 Pearson Education, Inc. Publishing as Pearson Addison-Wesley 1-12 What is Usability Testing? Human Subjects Protocols –You must be fully aware of the regulations imposed by the various institutions and regulatory bodies that pertain to your experimental design –The U.S. Department of Health and Human Services Web site

Copyright © 2008 Pearson Education, Inc. Publishing as Pearson Addison-Wesley 1-13 What is Usability Testing? Advantages –Minimize help desk calls –Increase product loyalty –Provide benchmarks for future products Limitations –Artificial context –Not definitive of product acceptance –Skewed sample of users –Not always efficient

Copyright © 2008 Pearson Education, Inc. Publishing as Pearson Addison-Wesley 1-14 What is Usability? – Phases of a Usability Test Design the Test Prepare for the Test Perform the Test Process the Data

Copyright © 2008 Pearson Education, Inc. Publishing as Pearson Addison-Wesley 1-15 Design the Test Why: Define the Purpose What: Define Your Concerns and Goals What: Define the Tasks What: Create the Scenarios What: Define the Measurements How: Define the Test Method

Copyright © 2008 Pearson Education, Inc. Publishing as Pearson Addison-Wesley 1-16 Design the Test Where: Determine the Location of the Tests

Copyright © 2008 Pearson Education, Inc. Publishing as Pearson Addison-Wesley 1-17 Design the Test Who: Select Participants, Testers, and Observers

Copyright © 2008 Pearson Education, Inc. Publishing as Pearson Addison-Wesley 1-18 Design the Test Participants should be real users You do not always need to test a great many users The people you recruit should have the following basic characteristics: –Availability –Responsiveness –Objectivity

Copyright © 2008 Pearson Education, Inc. Publishing as Pearson Addison-Wesley 1-19 Design the Test Tester roles include the following: –Administrator –Moderator –Data logger –Technician –Prototype expert Potential observers include the following: –Other design team members not involved in the test –Clients –Programmers responsible for the final product

Copyright © 2008 Pearson Education, Inc. Publishing as Pearson Addison-Wesley 1-20 Prepare for the Test When: Create a Test Schedule –Project level You must build time for (iterative!) testing into the overall project plan right from the conception of the project; even if it’s just an estimate –Test preparation level Scheduling the testers, the participants, and the facility (if it’s specialised, or on site in the field) –Test and task execution level Must account for fatigue Organisation and preparation (if the user is going to do a 30-minute task, you’ll need an hour [to greet, settle in, debrief, etc.) – and more time between test participants)

Copyright © 2008 Pearson Education, Inc. Publishing as Pearson Addison-Wesley 1-21 Prepare for the Test Writing Scripts –Greeting the Participant –Preliminary Interview –Providing Instructions –Monitoring the Test –Debriefing the Participant Running a Pilot Test –Be organized –Be presentable

Copyright © 2008 Pearson Education, Inc. Publishing as Pearson Addison-Wesley 1-22 Perform the Test Test Phases –Pre-Test Greet the participant. Have the participant sign the informed consent form. Have the participant fill out any pre-test questionnaire. Proceed with scripts. –During the Test Maintain a log or observation check list for each task. Create a problem list to capture anything that is not covered by the check list. Notate problems and jot down any hypotheses that occur to you about the problems.

Copyright © 2008 Pearson Education, Inc. Publishing as Pearson Addison-Wesley 1-23 Perform the Test Test Phases –Post-Test Debrief the participant. –post-test questionnaire –verbal interview Thank the participant and provide compensation. Collect, summarize, and organize test data. Reset the room for the next participant.

Copyright © 2008 Pearson Education, Inc. Publishing as Pearson Addison-Wesley 1-24 Process the Data Activities Performed on the Day of the Test –Collecting Data –Summarizing Data –Organizing the Material Follow-Up Activities –Categorizing –Analyzing Quantitative Data Qualitative Data

Copyright © 2008 Pearson Education, Inc. Publishing as Pearson Addison-Wesley 1-25 Process the Data Documenting (remember – it’s all about getting answers to make a better product!) –Identify problems Severity Frequency Errors of omission (user didn’t see feature) Errors of commission (user misinterpreted/misoperated feature) –Prioritize problems –Theorize reasons –Theorize solutions –Identify successes –Identify areas of uncertainty

Copyright © 2008 Pearson Education, Inc. Publishing as Pearson Addison-Wesley Test settings A test may be a classic formal usability test –In a laboratory, as described here It’s actually rare to get all the users to a really well equipped laboratory May be some compromise with a temporary ‘lab’ set up somewhere close to where the users are found It may be done in the ‘field’ –At the site where the users normally work –Possibly just in terms of them using the new software for their actual work (i.e. no fixed protocol) This is a field study, or field test At the loosest, this is a beta-test release, where there is relatively little systematic measurement of the users (maybe a questionnaire and volunteered qualitative feedback) Has advantage of much longer use than in lab 1-26