Interpretive Evaluation Agenda Simple user modeling Interpretive Evaluation - Motivation - Methods Ethnography Fitt’s Law

Fall 2002CS/PSY Simpler User Modeling How do attributes of users influence the design of user interfaces? Are there some design guidelines that we can derive from different attributes?

Fall 2002CS/PSY User Profiles Attributes:  attitude, motivation, reading level, typing skill, education, system experience, task experience, computer literacy, frequency of use, training, color-blindness, handedness, gender,… Novice, intermediate, expert

Fall 2002CS/PSY Motivation User  Low motivation, discretionary use  Low motivation, mandatory  High motivation, due to fear  High motivation, due to interest Design goal  Ease of learning  Control, power  Ease of learning, robustness, control  Power, ease of use

Fall 2002CS/PSY Knowledge & Experience Experience tasksystem  lowlow  highhigh  lowhigh  highlow Design goals  Many syntactic and semantic prompts  Efficient commands, concise syntax  Semantic help facilities  Lots of syntactic prompting

Fall 2002CS/PSY Job & Task Implications Frequency of use  High - Ease of use  Low - Ease of learning & remembering Task implications  High - Ease of use  Low - Ease of learning System use  Mandatory - Ease of using  Discretionary - Ease of learning

Fall 2002CS/PSY Evaluation Predictive  Discount Usability (Mon)  Cognitive Modeling-GOMS family (Wed)  Cognitive Modeling-contextual (next Mon) Interpretive (today) User testing (later)

Fall 2002CS/PSY Approaches Experimental (Lab studies, quantitative)  Typically in a closed, lab setting Manipulate independent variables to see effect on dependent variables Naturalistic (Field studies, qualitative)  Observation occurs in “real life” setting Watch process over time “Ecologically valid”

Fall 2002CS/PSY Interpretive Evaluation Experimental: Formal and objective Interpretive: More subjective  Concerned with humans, so no objective reality  Sociological, anthropological approach Users involved, as opposed to predictive approaches

Fall 2002CS/PSY Beliefs Sees limitations in scientific hypothesis testing in closed environment  Lab is not real world  Can’t control all variables  Context is neglected  Artificial, short tasks

Fall 2002CS/PSY IE Methods A number of different methods or techniques in this area exist  Ethnography Our main focus  Contextual inquiry More specific form of ethnography with a focus on asking questions  Field study Common notion, often equated with ethnography  Observational study Much more informal, just watching users  …

Fall 2002CS/PSY Ethnography Deeply contextual study Immerse oneself in situation you want to learn about (anthropological and sociological roots)  Observing people in their cultural context Interpretation of data is primary Behavior is meaningful only in context

Fall 2002CS/PSY Philosophy Argues that formal environment of controlled study is artificial --- Experimenter wields “power” over subject So … get into working environment of user -> Interpretation is primary, rather than data

Fall 2002CS/PSY Objectives Understanding the user  Understand goals and values  Understand individual’s or group’s interactions within a culture  Try to make tacit domain knowledge explicit  Do this in an unbiased fashion  For UI designers: Improve system by finding problems in way it is currently being used

Fall 2002CS/PSY Techniques In person observation Audio/video recording Interviews “Wallow in the data”

Fall 2002CS/PSY Observation is Key Carefully observe everything about users and their environment Think of describing it to someone who has never seen this activity before What users say is important, but also non- verbal details

Fall 2002CS/PSY Observations Things of interest to evaluator  Structure and language used in work  Individual and group actions  Culture affecting work  Explicit and implicit aspects of work Example: Office work environment  Business practices, rooms, artifacts, work standards, relationships between workers, managers, …

Fall 2002CS/PSY Interviews Important Have a question plan, but keep interview open to different directions Be specific Create interpretations together with users At end, query “What should I have asked?” Record interviews

Fall 2002CS/PSY Steps 1. Preparation  Understand organization policies and work culture  Familiarize yourself with system and its history  Set initial goals and prepare questions  Gain access and permission to observe & interview 2. Field study  Establish rapport with users  Observe/interview users in workplace and collect all different forms of data  Follow any leads that emerge from visits  Record the visits Rose et al ‘95

Fall 2002CS/PSY Steps 3. Analysis  Compile collected data in numerical, textual and multimedia databases  Quantify data and compile statistics  Reduce and interpret data  Refine goals and process used 4. Reporting  Consider multiple audiences and goals  Prepare a report and present findings

Fall 2002CS/PSY One Technique Affinity Diagram Process  Write down each quote/observation on a slip of paper  Put up on board  Coalesce items that have affinity If they are saying similar things about an issue  Give names to different groups (colors too)  Continue grouping subgroups  A hierarchy will be formed

Fall 2002CS/PSY Why Useful? Can help designer gain a rich and true assessment of user needs  Help to define requirements Uncovers true nature of user’s job  Discovers things that are outside of job description or documentation Allows you to play role of end-user  Can sit in when real users not available Open-ended and unbiased nature promotes discovery  Empirical study and task analysis are more formal – ethnography may yield more unexpected revelations

Fall 2002CS/PSY Types of Findings Can be both  Qualitative Observe trends, habits, patterns, …  Quantitative How often was something done, what per cent of the time did something occur, how many different …

Fall 2002CS/PSY Drawbacks Time required  Can take weeks or months Scale  Most use small numbers of participants just to keep somewhat manageable Type of results  Highly qualitative, may be difficult to present and use Acquired skill  Identifying and extracting “interesting” things is challenging

Fall 2002CS/PSY Ethnomethodology Concurrent/informed ethnography  Study is being done in conjunction with a system being developed  + Helps keep focus on user throughout design  - Requires lots of time and coordination

Fall 2002CS/PSY Cooperative Evaluation User is viewed as collaborator in evaluation, not a subject  “Friendly approach” Relaxed version of think-aloud  Evaluator and participant can ask each other questions

Fall 2002CS/PSY CE Methods Seeks to detect errors early in a prototype Experimenter uses tasks, also talks to participant throughout, asks questions

Fall 2002CS/PSY Low Level Models Fitt’s Law  Models movement times for selection tasks Basic idea: Movement time for a well- rehearsed selection task  Increases as the distance to the target increases  Decreases as the size of the target increases

Fall 2002CS/PSY Components ID - Index of difficulty ID = log 2 ( 2A/W ) bits result Both quantities are distances so unitless result width tolerance of target distance to move

Fall 2002CS/PSY Components MT - Movement time MT = b * ID or MT = a + b*ID MT is a linear function of ID

Fall 2002CS/PSY Original Experiment 1-D AW

Fall 2002CS/PSY Exact Equation Run empirical tests to determine a and b in MT = a + b*ID Will get different ones for different input devices and ways the device is used MT ID

Fall 2002CS/PSY Common Equation MT = a + b log 2 (A/W + 1) Provides useful numbers

Fall 2002CS/PSY Questions What do you do in 2D? Where can this be applied in user interface design?