task analysis

TASK ANALYSIS

공병돈

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TASK ANALYSIS

Overview

Task analysis ? Study of the way people perform tasks with existing systems .

Technics – Decomposition Taxonomic classification Listing things used & actions performed

Source of Information – Existing documentation Observation Interviews

Using to Design – Manual & Documentation New systems

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TASK ANALYSIS Introduction

Process of Analyzing the way people perform their job

– what people do

– what things they work with

– what they must knowEx) in order to clean the house

• get the vacuum cleaner out • fix the appropriate attachments• clean the rooms• when the dust bag gets full, empty it• put the vacuum cleaner and tools away

must know about:• vacuum cleaners, their attachments, dust bags,

cupboards, rooms etc.

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TASK ANALYSISDifferences Between task analysis

and other technics

System Analysis

VS Task Analysis

System design focus The user

Cognitive model VS Task analysis

Internal mental stagefocus

Extenal action

Practiced unit task Whole job

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TASK ANALYSISApproaches to task analysis

Task decomposition - splitting task into (ordered) subtasks

Knowledge based techniques- what the user knows about the task

and how it is organised

Entity/object based analysis- relationships between objects, actions and

the people who perform them

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TASK ANALYSISTask Decomposition

Aims : Describe the actions people do Structure them within task subtask hierarchy Describe order of subtasks

Hierarchical Task Analysis (HTA)

0. in order to clean the house 1. get the vacuum cleaner out 2. get the appropriate attachment 3. clean the rooms 3.1. clean the hall 3.2. clean the living rooms 3.3. clean the bedrooms 4. empty the dust bag 5. put vacuum cleaner and attachments away

◈ Plan 0 do 1 - 2 - 3 - 5 in that order. when the dust bag gets full do 4

◈ Plan 3 do any of 3.1, 3.2 or 3.3 in any order depending on which rooms need cleaning

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Stopping rule -> Depend on purpose of task analysis

P*C rule

Complex motor response or Internal Decision Making

0. in an emergency 1. read the alarm 2. work out appropriate

corrective action 3. perform corrective action

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Make Pot

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fixed sequence optional tasks

wait for events

cycles

time-sharing

mixtures

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TASK ANALYSIS Waiting …

is waiting part of a plan?… or a task?

generally– task – if ‘busy’ wait• you are actively waiting

– plan – if end of delay is the event• e.g. “when alarm rings”, “when reply

arrives”

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Entity/object based analysis- relationships between objects, actions and

the people who perform them

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TASK ANALYSISKnowledge-Based Analysis

Listing all objects & actions -> Build texonomy

Aim : Understand needed knowledge about task Help production teaching material Common knowledge between differ task

motor controlssteering steering wheel, indicatorsengine/speed direct ignition, accelerator, foot brake gearing clutch, gear sticklights external headlights, hazard lights

internal courtesy light

wash/wipewipers front wipers, rear wiperswashers front washers, rear

washersheating temperature control, air direction, fan, rear screen heaterparking hand brake, door lockradio numerous!

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Three types of branch point(TDH:Task description hierachy))XOR : normal taxonomy -> ( )AND : multiple classifications -> / OR : weakest case -> { }Kitchen item AND/____shape XOR/ |____dished mixing bowl, casserole, saucepan, soup bowl, glass/ |____flat plate, chopping board, frying pan//____function OR {____preparation mixing bowl, plate, chopping board {____cooking frying pan, casserole, saucepan {____dining XOR |____for food plate, soup bowl, casserole |____for drink glassPlate as Kitchen item/shape(flat)/function{preparation,dining(for food)}/

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TDH in actions

kitchen job OR|____ preparation beating, mixing|____ cooking frying, boiling, baking|____ dining pouring, eating, drinking

What action can do we do with a choping board?

We Can capturing all action of task !!

Generification – do not use complete KRG

Kitchen item/function{preparation,dining}/

Kitchen item/shape(flat)/Function{preparation,dining(for food)}/

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USE of KRG (specific or generic) ex) Beating an egg in a mixing bowl

Kitchen job (preparation) using a kitchen item/shape(dished)/function{preparation}/

Kitchen job (preparation(beating)) using a kitchen item/shape(dished)/function{preparation}/

Kitchen job (preparation) using a kitchen /function{preparation}/

Useful for teaching purpose

generic

specific

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Entity/object based analysis- relationships between objects, actions

and the people who perform them

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TASK ANALYSISEntity-Relationship-Based Techniques

Cataloging & Examination of objects and actions

gardener

soil spade dig

It is the gardener who performs the digging acting upon the soil using the spade

Object Attribute ActionConcrete objects : simple things: spade, plough,

glasshouse

Actors : human actors - Vera, Sam, Tony, the customers non human actor - irrigation computer

Composite objects : sets: the team = Vera, Sam, Tony tuples: tractor may be < Fergie, plough >

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Object Attribute Action

Object Pump3 simple – irrigation pump Attributes:

status: on/off/faultycapacity: 100 litres/minute

agent – who performs the actions patient – which is changed by the action instrument – used to perform action

examples:Sam (agent) planted (action) the leeks (patient)Tony dug the field with the spade (instrument)

Object Attribute Action

ImplicitIndirectMessage

Role

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Example

Object Sam human actorActions:

S1: drive tractorS2: dig the carrots

Object Vera human actor– the proprietor

Actions: as workerV1: plant marrow seedV2: program irrigation controller

Actions: as managerV3: tell Sam to dig the carrots

Object the men compositeComprises: Sam, Tony

Object glasshouse simpleAttribute:

humidity: 0-100%

Object Irrigation Controllernon-human actor

Actions:IC1: turn on Pump1IC2: turn on Pump2IC3: turn on Pump3

Object Marrow simpleActions:

M1: germinateM2: grow

Event : performance , spontaneous, timed

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Relationsobject-object

social - Sam is subordinate to Vera spatial - pump 3 is in the glasshouse

action-object agent (listed with object) patient and instrument

actions and events temporal and causal

‘Sam digs the carrots because Vera told him’

temporal relations use HTA or dialogue notations. show task sequence show object lifecycle

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Application

0. in order to grow marrows 1. Vera sows the marrow seed 2. marrow germinates 3. Vera programs controller 4. controller waters field 5. marrow grows 6. Sam hoes 7. Tony havests marrows

Plan 0 : 1-2-5-when crop is mature 7 when rainfall is low 3-4 when weeds grow 6

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Life Cycle

0. life cycle of tractor

1. maintenance

2. cultivation

2.2 drive to field

2.3 cultivate field

2.4 drive to tool shed

2.5 put away

2.1 connect implement

2.1.2 fix plough

2.1.1. fix harrow

Plan 0. as require -2When tractor break down -1

Plan 2. 2.1-2.2-2.3-2.4-2.5

Plan 2. 1 one of 2.1.1 or 2.1.2 depending on job

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TASK ANALYSISSource of information and

data collection

Documentation - Supposed & Functions - Useful basic action & object

Observation- formal/informal, laboratory/field, Passive/Active

Interviews- Direct & Quick Way - Both Manager & Actual Worker

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TASK ANALYSIS

Extraction from transcripts– list nouns (objects) and verbs (actions)– beware technical language and context

`the rain poured’ vs. `I poured the tea’

Sorting and classifying– grouping or arranging words on cards– ranking objects/actions for task relevance – use commercial outliner

Source of information and data collection

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TASK ANALYSIS

Conceptual Manual– from knowledge or entity–relations based

analysis– good for open ended tasks

Procedural ‘How to do it’ Manual– from HTA description– good for novices– assumes all tasks known

Uses of Task Analysis

To make cups of tea

boil water –– see page 2empty pot

make pot –– see page 3wait 4 or 5 minutes

pour tea –– see page 4

–– page 1 ––

Make pot of tea

warm potput tea leaves in potpour in boiling water

–– page 3 ––

once water has boiled

Cookey in eight easy lessonLec1. preparation – dished utensilsLec2. preparation – flat utensilsLec3. job for food preparationLec4. cooking – dished utensils…Lec8. dining – graceful eating and drinking(followed by four course dinner)

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TASK ANALYSIS

Requirements capture and systems design– lifts focus from system to user– What should be in new system?– What novel features are to be?

Detailed interface design– taxonomies suggest menu layout– object/action lists suggest interface objects– task frequency guides default choices– existing task sequences guide dialogue design

Task analysis is never complete – Support the way people want to work

Uses of Task Analysis

task analysis

Documents