Fall 2002 CS/PSY 6750 1

Task Analysis

• Analyzing and describing how people do their jobs/work -> Go to their environment

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

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Components

• Three key components to include in discussing how people work Activities Artifacts Relations

• Don’t just focus on computer system artifacts and interactions

• Study related processes and objects in the environment that people may use and involve Example: office env---papers, whiteboards, etc.

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Task Analysis Focus

• Focus on observable behaviors What are the practices, methods, steps,

objects, …, used?

• Observe users, what they do, less so how they do it

• Not on internal cognitive state of user

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Input & Output

• Gather data: Documentation Interviews Observation Surveys/questionnaires Automatic data recording/tracking

• Represent Data: Lists, outlines, matrices Narratives Hierarchies & Networks Flow charts

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Data to be Gathered

• Information about users• Description of environment

Where the tasks will be performed• Major goals of the job

What will result in a successful end state?

• User preferences & needs Before they even start: coffee, pen,

notebook, log sheets…

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Data to be Gathered …

• Tasks & Subtasks: Physical Cognitive Communication

• Conditions under which these tasks are done• Results/outcomes of tasks• Requirements to perform task:

Information Communication with others Equipment

Must includeShould includeCould includeExclude

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Data Gathering Tools: Docs

• Documentation Often contains description of how the tasks should

be done (rather than how they are currently being done)

Standards Manuals Histories Best Practices

• Domain Expert Description Expert describes how process should work, how

tasks should be done “Knowledge-based” discovery

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DGT: Interviews

• Interviews: Structured

EfficientRequire training

UnstructuredInefficientNo training

Semi-structuredGood balanceOften appropriate

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Semi-structured Interviews

• Predetermine data of interest• Plan for effective question types

How do you perform task x?Why do you perform task x?Under what conditions do you perform task x?What do you do before you perfom…?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…?What is the result or consequence of NOT…?

See: Gordon & Gill, 1992; Graesser, Lang, & Elofson, 1987

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DGT: Observation

• Observation In situ, watch users do what they do Record with videotape

To watch later, or again

Take lots of notes, sketches May require coding the video later Focus on specific task-relevant behaviors

in notes, but later convert to abstract subtasks

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DGT: Questions

• Questions & Answers Questionnaires

Exploratory vs. confirmatoryOpen-ended vs. categorical

(exhaustive)What do you need to perform..? (list)Which of the following is most

important to perform…? (select)

If you ask it, use it. If you won’t/can’t use it, don’t ask it.

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DGT: Think-aloud

• Questions & Answers, cont’d… Think-aloud protocol

Person talks about what they are doing, while they are doing it (or just before or after)

Observer can ask probe questionsWhy did you just do that?

Note: Probe questions affect performance, as does thinking aloud.

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DGT: Logging

• Automatic tracking Keystroke/mouse click monitoring Timers Logs Physical location/movement trackers

Cell phonesAware Home

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Representing Data: Outlines

• Lists, outlines, matrices Use expanding/collapsing outline tool Add detail progressively Know in advance how much detail is enough Can add linked outlines for specific subtasks

Good for sequential tasks Does not support parallel tasks well Does not support branching well

Example, next slide

Using a lawnmower to cut grassStep 1. Examine lawn

Make sure grass is dryLook for objects laying in the grass

Step 2. Inspect lawnmowerCheck components for tightness

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

Make sure grass bag connector is securely fastened to bag adaptor

Make sure that deck cover is in placeCheck for any loose parts (such as oil caps)Check to make sure blade is attached securely

Check engine oil levelRemove oil fill cap and dipstickWipe dipstickReplace dipstick completely in lawnmowerRemove dipstickCheck that oil is past the level line on dipstick…

Task Outline

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RD: Narratives

• Narratives Describe tasks in sentences Often expanded version of list or outline More effective for communicating

general idea of task Not effective for details Not effective for branching tasks Not effective for parallel tasks

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RD: Hierarchies

• Hierarchical Task Analysis (HTA) Graphical notation & decomposition of

tasks Tasks as sets of actions Tasks organized into plans

Clusters of subtasks with a preferred order and prerequisite conditions

HTA

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Example Task Clusters

• Fixed sequence• Optional tasks• Waiting events• Cycles• Time-sharing• Discretionary

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RD: Networks

• Network / Entity-Relationship Diagrams Objects/people with links to related objects

Stress relationship between objects and actions

Links described functionally and in terms of strength

Task: Develop design for final projectobjects - pens, paper, drawing tools, etc.actors - Mary, Bob, Sallycomposite objects - the “team”

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Methodology

• Often list attributes, actions of objects

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

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

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RD: Flow Charts

• 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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Flow ChartStart

Continue? Document

Input

Display

ManualOperation

End

Y

N

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Summary of Task Analysis

• Determine the data you need• Gather it using various appropriate

methods and techniques• Represent the tasks and subtasks,

plus other related information• Use this data to improve design

• Note: Be efficient!