4 Task Analysis2!17!09
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Transcript of 4 Task Analysis2!17!09
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Dr. Jill Drury, [email protected]
n vers y o assac use s owe91.527 Intro to HCI
e ruary
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What well cover
r nc p es oethnography
Several types of task
analysis: Environment
Hierarchical
O erational se uence
Workload analysis
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Principles of ethnography
Use extended direct observation of the target culture tounderstand tacit behavior
o no s ar w ypo eses an use a sem -s ruc ureapproach
Observe how artifacts are used to accomplish real goals
Do not distort the meaning of the target cultureslanguage through a literal translation into the
Learn to speak the target cultures language
Do not have implicit assumptions that might biasnterpretat on, an test exp c t assumpt ons r gorous y
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Example: ATM
Goal: Obtain $100 in cash
Preconditions: Actor has card, knows PIN,has cash in account
Actor System
1a. Presents card
1b. Reads/validates account #1c. equests
2a. Enters PIN
2b. Indicates PIN entered
2c. Reads/validates PIN2d. Presents action choices
. .
. .
Postconditions: Actor has $100 in cash, System ensuresaccount balance is decremented by $100
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Use cases
xamp e: p oa ng g tplans to a UAV
Goal: Program the UAV to fly aparticular pattern
,
Actor System
1a.Enters command to set waypoint1b. Indicates readiness to accept waypoint
2a.Enters 1st waypoint
2b.Indicates 1st waypoint entry done
c. ea s va a es wapo n3a. Repeats 2a - c for other waypoints
4a. Enters command to upload waypoints
4 . n cates new g t pat s act ve
Postconditions: Aircraft will fly designated patternPhoto: Lou Nocca
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Well cover four types
or env ronment ana ys s
Hierarchical task analysis
diagrams
Workload diagrams
At Scripps Institute of Oceanography,
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researc ers eve ope a mouse t atcan be used under water
(photo courtesy of Scripps Institute)
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Work environment analysis
Typical office or not?
Noise?
Lighting?
Interruptions?
Describe socio-culturalenvironment
Draw implications forinterface design
ee pages - n
Mayhew for example
UPS drivers use a handheld computer
while standing and walking outside9
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Example work environment analysis: UAV SAR
Ph sical la out
Outside; could be cold No precipitation (a/c cant fly)
mosp ere
Tense, life and death situation
On your own, far from support
Socio-cultural environment
First responders are resourceful,,
Photo: Lou Nocca
Implications for interface design
Efficient to operate Prevents errors
Contains highly visible controls
Able to be worked using gloves 10
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Hierarchical task analysis
tart y ent y ng as c user tas s romobservation/interview materials
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Identify the major steps needed to do the activity
In cases where there are alternative ways to do the task,
Keep decomposing steps until you get to the lowestlevel description that makes sense for your analysis
Refine by working directly with users
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Example: Borrow a library book (Sharp et al.)
access.
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Task anal sisExample: UAV Search-and-Rescue (SAR) MissionAssumes: batteries arechar ed, team is alread Scope: from after
UAV SAR (0)
at rescue site base,
frequency notification isposted, and equipment isun acked
equ pment was unpac e
at site but not assembled,through landing of aircraft
Prepare for mission (1.0) Execute mission (2.0)
PrepareEquip-
PrepareAircraft
PrepareMission Para-
LaunchAircraft
MonitorMission
LandAircraft
ment (1.1) (1.2) meters (1.3) (2.1) (2.2) (2.3)
Tasks based on my experience flying Procerus
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Task anal sisExample: UAV Search-and-Rescue (SAR) Mission
repare or m ss on .
PrepareEquip-
ment (1.1)
PrepareAircraft
(1.2)
PrepareMission Para-meters (1.3)
Turn On &Distribute
CableTogether
InsertZero
AttitudePitotTube
TrimAircraft
EnterWaypts
Insert a/c
Walkie-Talkies
(1.1.3)
Equipmt(1.1.2)
(1.1.1)(1.3.2)Test
(1.2.3)
(1.2.2) (1.3.1)(1.2.1)
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Task anal sisExample: UAV Search-and-Rescue (SAR) Mission
UAV SAR (0)
Execute mission (2.0)
Launch Monitor LandAircraft
(2.1)Mission
(2.2)Aircraft
(2.3)
MonitorStatus(2.2.1)
WatchVideo forVictims
ChangeCourse as
Needed
Move tolaunchpoint
TossA/C
(2.1.2)
Switch toComputerin Control
Send landcommand
2.3.1
Force A/CDown withRadio cntl
2.2.2 . .
Watch battery level (2.2.1.1)
Ensure GPS lock (2.2.1.2)
Monitor weather (2.2.1.3)
Enter loiter point if evidence
of victim nearby (2.2.3.1)Upload loiter point (2.2.3.2)
. . 2.1.3 . .
PLAN: if conditions turnunfavorable, immediately beginlanding sequence (2.3)
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Task analysis
perat ona sequence agrams or escr ngteam members actions
Graphic presentation of user tasks as they relatesequentially
Facilitates showing what multiple team members
are doing simultaneously ows m ng, ec s on po n s, ype o ac on
Purpose:
Useful for anal zin com lex s stems re uirin time-
critical decision making
Enables analysts to tease apart which team membersare doin what and when the are doin it
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Example
Illustration showsactions by twocrew members
ur ng a one-minute period
Legend is on nextpage
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Example
Legend for operational sequence diagram example
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Example: UAV preparation
Illustration shows
actions by twocrew members to
,necessary, zerothe attitude
adjustmentsett ng nresponse to achecklist item
rew o sthe aircraft whileCrew #1 checksthe settin
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Introduction to team workload analysis
time, so start with operational sequence diagrams Then characterize how bus each o erator is at each
moment based on direct observations
Are they manipulating an input device, monitoring the, ,
Could they do something more, or are they fully occupied?
Use estimates: 25%, 50%, 75% or 100% occupied
urpose: See where bottlenecks/overloads exist that could be
alleviated by less workload-intense approach
Determine if work could be redesigned to be done by fewer
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Task analysis
:
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