1. User-Centered Design and Development Instructor: Franz J. Kurfess Computer Science Dept. Cal Poly San Luis Obispo FJK 2005

2. Copyright Notice These slides are a revised version of the originals provided with the book “Interaction Design” by Jennifer Preece, Yvonne Rogers, and Helen Sharp, Wiley, 2002. I added some material, made some minor modifications, and created a custom show to select a subset. –Slides added or modified by me are marked with my initials (FJK), unless I forgot it … FJK 2005

3. 484-W09 Quarter The slides I use in class are in the Custom Show “484-W09”. It is a subset of the whole collection in this file. Week 8 contains slides from Chapter 14 of the textbook. FJK 2005

4. Chapter 14 Testing and Modeling Users FJK 2005

5. Chapter Overview user testing DECIDE framework for user testing experiments –variables and conditions –data collection and analysis predictive models –GOMs –keystroke level model FJK 2005

6. Motivation in addition to asking users about their experiences or tasks, it may be necessary to conduct tests where they perform tasks ideally, these tests should be done with the final product –in practice, this is often not feasible –user testing can also be done on prototypes to find out how well the general approach works user modeling tries to predict user performance for tasks performed on a system

7. FJK 2005 Objectives become familiar with the main principles and constraints of user testing be aware of the differences between user testing, usability testing and research experiments be able to design simple experiments become familiar with the GOMS user model, the keystroke level model, and Fitts’ law determine when these techniques can be applied know how to do a keystroke level analysis

8. Testing & modeling users

9. The aims Describe how to do user testing. Discuss the differences between user testing, usability testing and research experiments. Discuss the role of user testing in usability testing. Discuss how to design simple experiments. Describe GOMS, the keystroke level model, Fitts’ law and discuss when these techniques are useful. Describe how to do a keystroke level analysis.

10. Activity: Portal and Blackboard in K-12 Education the SLO County Office of Education is using a version of the portal and Blackboard identify an strategy to perform user testing in their context –goals and questions –paradigm and techniques –practical aspects: typical tasks, typical users test conditions, running tests –ethical issues –evaluation, analysis, and presentation of data FJK 2005

11. Activity: Tablets in Grade School development of an educational Graphical Information System (GIS) –team of CSC students advised by Michael Haungs, Rollin Strohman –use of tablet PCs as client platforms they collaborate with a grade school teacher who wants to use their system in a lesson on California missions sketch a usability evaluation strategy for this context FJK 2006

12. Activity Guidelines goals and questions paradigm and techniques practical aspects: –typical tasks, typical users –test conditions, running tests ethical issues evaluation, analysis, and presentation of data FJK 2006

13. Activity cont: Constraints student age no tablet PC experience main objective for the teacher is student learning about California missions limited time unfamiliar environment for students –outside of their classroom –foreign people present –use of new computer equipment FJK 2006

14. Experiments, User Testing and Usability Testing experiments –test hypotheses to discover new knowledge –investigate the relationship between two or more things variables user testing –applied experimentation –developers check that the system being developed is usable by the intended user population for their tasks usability testing –uses a combination of techniques user testing user satisfaction questionnaires

15. User Testing vs. Research User testing Aim: improve products Few participants Results inform design Not perfectly replicable Controlled conditions Procedure planned Results reported to developers Research experiments Aim: discover knowledge Many participants Results validated statistically Replicable Strongly controlled conditions Experimental design Scientific paper reports results to community

16. User Testing goals and questions focus on user performance –how well do users perform tasks with the product comparison of products or prototypes common major part of usability testing focus is on –time to complete task –number and type of errors informed by video and interaction logging user satisfaction questionnaires provide feedback –experiences of users with the product –data about users’ opinions

17. FJK 2005 User Testing with DECIDE Determine the goals and Explore the questions Choose the paradigm and techniques Identify practical issues Deal with ethical issues Evaluate, analyze, and present data

18. FJK 2005 Goals and Questions generic goal is usually related to usability issues –interaction –navigation specific goals are influenced by tasks, system, user aspects –how well do certain users perform a particular task usability hypothesis –it is sometimes helpful to formulate a hypothesis to be confirmed or rejected

19. Paradigms and Techniques the main paradigm is usability testing –confusion between “user testing” and “usability testing” is common recording user data –video –interaction logging questionnaires –user impressions, satisfaction interviews –more open format for user impressions FJK 2005

20. Task Design task selection –tasks that are critical for the user’s overall job –tasks that illustrate the use of the system –frequently performed tasks –“completion” tasks are often used performance measurement –ideally quantifiable see “Data Collection” slide –realistic typical for users in their regular environment FJK 2005

21. User Selection “typical” users –what are typical users? –how can typical users be found? –typical users may not be the best choice volunteers as test participants –self-selection may lead to bias users comfortable with computers confident about their performance assigned participants –may be reluctant to collaborate –may intentionally perform poorly FJK 2005

22. Testing Conditions usability lab –or other controlled space major emphasis on –selecting representative users –developing representative tasks 5-10 users typically selected tasks usually last no more than 30 minutes test conditions should be the same for every participant informed consent form –overview of the task –expectations –explains ethical issues

23. Data Collection type of data (Wilson & Wixon, ‘97) –time to complete a task –time to complete a task after a specified time away from the product –number and type of errors per task –number of errors per unit of time –number of navigations to online help or manuals –number of users making a particular error –number of users completing task successfully

24. Running the Tests preparation –reserve room, invite participants, check licencing issues, install systems, … schedule –times and activities script –activities of the testers –activities to be performed by the participants equipment setup pilot run aftermath FJK 2005

25. Ethical Issues informed consent form setup of facilities and experiments –observation facilities one-way mirrors closed-circuit cameras –recording facilities audio, video interaction logging participant discomfort –participants can interrupt or abort the experiment at any time –contingency plans for dealing with such problems FJK 2005

26. Evaluation, Analysis, and Presentation of Data high-level evaluation –identification of significant events or trends statistical analysis –maximum, minimum, average, mean, standard deviation –restricted to quantifiable aspects in-depth evaluation –careful observation and analysis of specific aspects unbiased, objective presentation –avoid secondguessing what stakeholders might want to hear –don’t suppress unpleasant outcomes FJK 2005

27. Usability Engineering Orientation current level of performance minimum acceptable level of performance target level of performance

28. How many participants is enough for user testing? largely a practical issue depends on: - schedule for testing - availability of participants - cost of running tests typically 5-10 participants some experts argue that testing should continue until no new insights are gained

29. Experiments predict the relationship between two or more variables independent variables –manipulated by the experimenter –typical experimental designs have one or two independent variables dependent variable –depends on the independent variable –beyond the control of the experimenter

30. Experimental Designs different participants –a single group of participants is allocated randomly to the experimental conditions same participants –all participants appear in both conditions matched participants –participants are matched in pairs e.g., based on expertise, gender match criteria should be relevant for the task

31. Advantages & Disadvantages

32. Predictive Models evaluating products or designs without directly involving users psychological models of users are used to test designs less expensive than user testing usefulness limited to systems with predictable tasks –telephone answering systems, mobile phones, etc. based on expert behavior –assumes experts or experienced users

33. GOMS Goals –the state the user wants to achieve e.g., find a website Operators –the cognitive processes and physical actions performed to attain those goals e.g., decide which search engine to use Methods –how to accomplish the goals e.g., drag mouse over field, type in keywords, press the go button Selection rules –determine which method to select developed by Stu Card, Tom Moran, and Alan Newell (Card et al., 1983)

34. Keystroke Level Model quantitative refinement of the GOMS model allows predictions to be made about how long it takes an expert user to perform a task –identifies basic actions involved –time is measured for each action –overall time is computed sum of individual actions in simple cases applied by measuring user interaction activities –keystrokes, mouse movements –mental preparation, hand re-positioning

35. Response times for keystroke level operators

36. Fitts’ Law predicts the time to point at an object using a device –function of the distance from the target object and the object’s size –the further away and the smaller the object, the longer the time to locate it and point time to locate an object is important for some devices and activities –handheld devices like mobile phones –computer games –navigation in multi-screen Web pages may indicate the use of alternatives –default actions, keyboard shortcuts formulated by Paul Fitts (Fitts, 1954)

37. Key Points user testing is a central part of usability testing testing is done in controlled conditions user testing is an adapted form of experimentation experiments aim to test hypotheses by manipulating certain variables while keeping others constant the experimenter controls the independent variable(s) but not the dependent variable(s) three types of experimental design –different-participants, same-participants, matched participants

38. A project for you … Use the web and other resources to research Jakob Nielsen’s claims about the efficacy of heuristic evaluation and Bill Bailey’s complaints that heuristic evaluation often identifies problems that are not serious and may not even be problems at all. Pretend that you are either Nielsen or Bailey and write a brief statement arguing your position. Provide practical evidence & evidence from the literature to support your position.

39. A project for you … Search the web for examples of the three different types of experimental designs. Write a brief critique of each.

40. A Project for you …Fitts’ Law Visit Tog’s website and do Tog’s quiz, designed to give you fitts! http://www.asktog.com/columns/022Designed ToGiveFitts.html