Jan 13, 2011 IAT 334 1

IAT 334Interface Design

Task Analysis______________________________________________________________________________________

SCHOOL OF INTERACTIVE ARTS + TECHNOLOGY [SIAT] | WWW.SIAT.SFU.CA

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Agendag Task Analysis g Evaluationg Predictive evaluation

– Heuristic evaluation– Discount usability testing– Cognitive walkthrough

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Task Conformanceg Task coverage

– Can system do all tasks of interest?

g Task adequacy– Can user do tasks?– Does system match real-world tasks?

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Task Analysisg Analyzing how people do their jobs

– Go to their environment– Learn about, analyze and describe their

tasks

g Examine users’ tasks to better understand what they need from interface and how they will use it

Task Analysisg Gather data about what users need

to do or accomplish

…then…

g Represent data for interpretation and use in design decisions

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Information to be Gatheredg Information about usersg Description of environment

– where the tasks will be performedg Major goals of the job

– what will result in a successful end state?

g User preferences & needs– before they even start: coffee, pen,

notebook, log sheets…Jan 13, 2011 IAT 334 6

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Task Analysisg Broad Focusg Observe users of current system(s)g Generate requirements

– Hierarchical task analysis– Knowledge-based task analysis– Entity-Relationship model

Data Gathering Techniques1. Observation2. Interviews & Contextual Inquiry3. Ethnographyalso…4. Surveys & Questionnaires5. Focus Groups & Expert Debriefing6. Competitive Product Review7. Documentation mining8. Data loggingJan 13, 2011 IAT 334 8

Information to be Gatheredg Tasks & Subtasks:

– Physical– Cognitive– Communication

g Conditions under which these tasks are done

g Results/outcomes of tasksg Requirements to perform task:

– Information– Communication with others– EquipmentJan 13, 2011 IAT 334 9

1. Observationg Watch users do what they do

– Typically from a distanceg Record with videotape

– May require coding video laterg Take lots of notes, sketchesg Focus on specific task-relevant

behaviors in notes, but later convert to abstract subtasks

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2. Interviewsg Engage the user more than just

watchingg Structured interviews

– Efficient, but requires trainingg Unstructured

– Inefficient, but requires no trainingg Semi-structured

– Good balance– Often appropriateJan 13, 2011 IAT 334 11

Semi-Structured Interviewsg Predetermine data of interestg Plan for effective question types

– How do you perform task x?– Why do you perform task x?– What information do you need to…?– Who do you need to communicate with to…?– What do you use to…?– What happens after you…?– What is the result or consequence of NOT…?

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3. Ethnographyg Deeply contextual inquiry

– “Wallow in the data”g “Live among” the usersg Understanding the full complexity of

behavior, in its complete social context

g Note: Techniques based in sociology and anthropology--the study of humans

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Commentg Techniques 1-3 are similar, but differ

in how “plugged in” or engaged the observer gets

g There are Pros and Cons of all these techniques

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More!g Often used in addition:

4. Surveys & Questionnaires5. Focus Groups & Expert Debriefing6. Competitive Product Review7. Documentation mining8. Data logging

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Existing Systemg Usually task analysis involves an

examination of an existing system, process or practice

g Watch what they do and how they do it

4. Surveys & Questionnaires

g Subjective answers in a quantitative format – What does this mean?

g Questions:– Exploratory vs. confirmatory– Open-ended vs. categorical (exhaustive)

– NB: If you ask it, use it. If you won’t/can’t use it, don’t ask it.Jan 13, 2011 IAT 334 17

Questionnairesg Likert scale common

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Evaluation Questionnaire

Please complete the following questionnaire by indicating how strongly you agree or disagree with the following statements. Your responses will be kept confidential and will be used only for improving the interface that you worked with in this experiment. 1. I felt that the computer agent’s help was worthwhile. 1-----2------3------4------5------6------7

Strongly Strongly Disagree Agree

2. I found the computer agent to be intrusive. 1-----2------3------4------5------6------7 Strongly Strongly Disagree Agree

3. I found the computer agent's help to be distracting. 1-----2------3------4------5------6------7 Strongly Strongly Disagree Agree

Typical Questionsg Rank the importance of each of these

tasks (give a list of tasks)g List the four most important tasks that

you perform (this is an open question)g List the pieces of information you need to

have before making a decision about X, in order of importance

g Are there any other points you would like to make? (open-ended opinion question; good way to end)

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5. Focus Groupsg Structured Interview with groups of

individuals– 3 to 10 persons– Use several different groups with different

roles or perspectives– Manage the interaction

• Avoid few people dominating the discussiong Focus on preferences and views, not

performanceg Relatively low cost, quick way to learn a

lotg Audio or video record, with permissionJan 13, 2011 IAT 334 20

6. Competitive Productsg Looking for both good and bad ideas

– Functionality– UI style

g Why are they successful or unsuccessful?

g What does successful really mean?– (Note: Successful does not equal

usable)Jan 13, 2011 IAT 334 21

7. Document Miningg Documentation

– Often contains description of how the tasks should be done

– Standards docs– Manuals– Histories– Best Practices

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8. Data Loggingg Automatically tracking:

– Keystroke/mouse clicks– Timers– Logs of transactions– Physical location/movement trackers

• Cell phones• GPS

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No Existing Systemg Gather documents, talk with

knowledgeable people, etc.

g Can still be useful to help generate requirements

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Task Analysis Focusg Not on internal cognitive state of

user (more on that in the near future)

g Focus on observable behaviors– Observe users, what they do, and how

they do it– What are the practices, methods, steps,

objects, …, used?

Now that you have observed…

g You have piles of notes, hours of video, surveys up to here…

g How can you digest and represent the data, to turn it into information?

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Describe Tasks

1. Task Outlines2. Narratives3. Hierarchies & Network Diagrams

– Hierarchical Task Analysis (HTA)– Entity-Relationship Diagrams

4. Flow Charts5. Card SortingJan 13, 2011 IAT 334 27

1. Task OutlineUsing a lawnmower to cut grass

Step 1. Examine lawna. Make sure grass is dryb. Look for objects laying in the grass

Step 2. Inspect lawnmowerc. Check components for tightness

1) Check that grass bag handle is securely fastened to the grass bag support

2) Make sure grass bag connector is securely fastened to bag adaptor3) Make sure that deck cover is in place4) Check for any loose parts (such as oil caps)5) Check to make sure blade is attached securely

d. Check engine oil level1) Remove oil fill cap and dipstick2) Wipe dipstick3) Replace dipstick completely in lawnmower4) Remove dipstick5) Check that oil is past the level line on dipstick

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2. Narrativesg Describe tasks in sentencesg Often expanded version of task

outlineg More effective for communicating

general idea of taskg Not effective for detailsg Not effective for branching tasksg Not effective for parallel tasksJan 13, 2011 IAT 334 29

3. Hierarchies & Networksg Hierarchical Task Analysis (HTA)

– Graphical notation & decomposition of tasks– Tasks as sets of actions– Tasks organized into plans (describes

sequence)g Network / Entity-Relationship Diagrams

– Objects/people with links to related objects– Links described functionally and in terms of

strength

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Hierarchical Task Decompositiong Decompose task into

– Subtasks• Multiple levels

– Plans describing ordering and conditions

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Common Plansg Fixed sequenceg Optional tasksg Waiting for eventsg Cyclesg Time-sharing -- parallelg Discretionary

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Entity-Relationshipg Object-based methodology, with a

real stress on relationship between objects and actions

g Involves– Concrete objects– Actors– Composite objects

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Exampleg Task: Develop design for final project

– Objects - Pens, paper, drawing tools, etc.

– Actors - Mary, Bob, Sally– Composite objects - The “team”

4. Flow Chartsg Flow Chart of Task Steps

– Combines Entity-relationship (network) with sequential flow, branching, parallel tasks.

– Includes actions, decisions, logic, by all elements of the system

– Abstracted– Mature, well-known, good tools

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5. Knowledge-based Analysisg List all objects and actions involved

in a task, then build a taxonomy of them

g Often times, work with domain expert to get help

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Methodologyg Sample:

– Get 3x5 cards– Put different object/action on each– Don’t worry about repetition at this

point!– Group into piles, subpiles, etc.

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Utilityg This type of task analysis can be

very useful when you’re writing a manual or some documentation– Taxonomy --- Document sections

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Methodologyg Often list attributes, actions of

objectsObject: pen simple Attribute: color: red writing: on/off

Object: Mary actor Actions: M1: make a sketch M2: organize meeting

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Useg Produce documentation

– Training, manuals, tutorialsg Requirements capture and system

design– Helps you define requirements

document– Helps decide what should be included

g Helps interface design– Hierarchical breakdown might feed

menu design

Summary:Data Gathering Techniques1. Observation2. Interviews & Contextual Inquiry3. Ethnographyalso…4. Surveys & Questionnaires5. Focus Groups & Expert Debriefing6. Competitive Product Review7. Documentation mining8. Data loggingJan 13, 2011 IAT 334 42

Summary:Describe Tasks

1. Task Outlines2. Narratives3. Hierarchies & Network Diagrams

– Hierarchical Task Analysis (HTA)– Entity-Relationship Diagrams

4. Flow Charts5. Card SortingJan 13, 2011 IAT 334 43