Contextual Inquiry

• A fact-based approach to understanding the reality of users’ goals, processes, and tasks.

• Puts designers, engineers, researchers, etc. directly in the “world” of the user to see, hear, feel, taste, smell, and better understand:

– the goals of the user

– the activities and specific behaviors users engage in to achieve those goals

– the places in which they occur

– the tools, supplies, etc. that are used

– the artifacts in the environment and their meanings

– etc.

• Provides rich, context-specific data from which to develop a shared understanding of users that will guide product development.

The Process

• Design the research• Recruit participants• Collect data

– interview (video taping optional)

• introduction

• Observation / interview

• wrap-up

– research notes

– artifacts

– “homework”, prework, etc. if applicable

• Analyze video, notes, visuals, artifacts, etc.• Synthesize results

Design and Evaluation

• Relation to the product life cycle ...(compare to product development cycle)

Front end

ConceptualDesign

analysis

Iterative designand testing

Design ofsupport mat'ls

Systemdisposal

ProductionImplementation

& evaluation Op. & Maint.

Ethnographic studies

User/function/task/environment analysis

User preferences/req'ts.

Functionalallocation*

Meta-models

Task analysisInterface designPrototypeDesign reviewEvaluationUsability testing

Develop/Influence

Design formanuf.

evaluationProduct

Monitor/test

QFD

User/Task Modeling

• What are user & task models?– Model - “a mathematical/physical system, obeying

specific rules and conditions, whose behavior is used to understand a real (physical, biological, human-technical, etc.) system to which it is analogous in certain respects.”(Bailey, 1989)

– A “good model” is one that adequately represents and can be used to generate testable hypotheses about the underlying system.

– User & task models - specifically focus on modeling the user’s goals and objectives, as well as his/her understanding of the task.

User/Task Modeling

• Dimensions of models …– Conceptual ………………. Computational

– Descriptive ………………..Normative

– Levels of specificity• Device …..….. task ……... meta-cognitive

User/Task Modeling

• Examples of modeling techniques

– Goal-means network

– GOMS

– Operator Function Model

– Decision Ladder

– Optimal control models

– Stochastic models

An example: making a PBJ sandwich ...

• Step 1: develop an understanding of the user and task (interviews, questionnaires, observation, etc.)

• Step 2: decide on a modeling framework (conceptual/computational, descriptive/normative, level of specificity, etc.)

• Step 3: build the model• Step 4: test/refine/modify• (Step 5: Use the model to support design, etc.)

Making a PBJ sandwich: Hierarchical Task Analysis (HTA)

1. Describe top-level goal:– “0. Make a peanut butter and jelly sandwich.”

2. Develop a plan for achieving that goal (including “error handling”):– Plan 0: Do 1-5, in order. If some ingredient is missing,

do 5.• “1. Get plate and knife.• 2. Collect ingredients.• 3. Assemble sandwich.• 4. Eat and enjoy.• 5. Put ingredients away.”

Making a PBJ sandwich: HTA

P lan 0 : D o 1 -5 in o rd er;if som e in g red ien t is m iss in g , s k ip to 5 .

1 . G e t p la te & kn ife 2 . C o llec t in g red ien ts 3 . A ssem b le san d w ich 4 . E a t & en joy 5 . P u t everyth in g aw ay.

0 . M ake a p b j

3. For each step in the plan, decide if more detail is required. Continue until sufficient detail is defined.

e.g., for step 1 …– Plan 1: Do 1-3; if no clean implements, do 4.

• 1.1 Go to cabinet and retrieve 1 plate.

• 1.2 Go to drawer and retrieve 1 knife.

• 1.3 Take knife and plate to table.

• 1.4 Wash knife/plate as necessary.

Making a PBJ sandwich: GOMS (Goals, Operators, Methods, & Selection rules)

1. Describe top-level goal:– “GOAL: Make a peanut butter and jelly sandwich.”

2. Describe a methods for achieving that goal (including selection rules and alternatives):

• GOAL: Get plate and knife.

• GOAL: Collect ingredients.

• GOAL: Assemble sandwich.

• Eat and enjoy.

• GOAL: Put ingredients away.

Making a PBJ sandwich: GOMS

3. For each “GOAL” in the method, describe a more detailed method.

e.g., • GOAL: Collect ingredients.

• • GOAL: Get bread.

• • GOAL: Get peanut butter.

• • GOAL: Get jelly.

• • • [Selection Rule:

Goto refrigerator

Goto pantry ]

Making a PBJ sandwich: GOMS

4. Continue until desired/necessary level of detail.

5. Use the (HTA or GOMS) model to:– Design documentation.– Predict performance.– Evaluate device/task designs.– Design.

Modeling more complex tasks: the Operator Function Model (OFM)

• Hierarchical/Heterarchical task decomposition– Activities are decomposed hierarchically (as in GOMS and HTA)

• Functions - highest-level activities (e.g., navigate, communicate, and aviate are pilot functions)

• Subfunctions - activities required to accomplish functions

• Task - lower level (more specific) activities to accomplish functions or subfunctions

• Actions - manual, cognitive, or perceptual

– Heterarchical structure accounts for concurrent activities, usually defined at the same level.

• Operators may choose from among these activities or the activities may result from system state(s).

Generic OFM

OFM example: Chinese dinner party

Steps (from Mitchell, 1998):

1. “Prepare a high-level written description of the system of interest …”

OFM example: Chinese dinner party

Steps (from Mitchell, 1998):

2. Identify the high-level activities the operator performs.

3. Define the heterarchy, specifying conditions for transitioning, initiating, or terminating activities.

OFM example: Chinese dinner party

4. Define the hierarchy, including conditions that start or end activities.

5. Validate the model. (Emphasis on direct observation, mapping actions into the model, resolving discrepancies.)

6. Refine the model as the system evolves.

OFM example: Chinese dinner party

• Completing the model …