© copyright by renee wy chow (2005) 1 sy de 542 eid for social systems march 28, 2005 r. chow...

© Copyright by Renee WY Chow (2005)

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SY DE 542

EID for Social Systems

March 28, 2005

R. ChowEmail: [email protected]

mailto:[email protected]






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EID for technical systems

• Nuclear power generation • Conventional (fossil fuel) power generation • Petrochemical processing • Medicine • Aviation

• Network management


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EID for social systems

Some examples:• Book House (Pejtersen, 1992)

• HyperErgo (Xu, Dainoff, Mark, 1999)

• Dirty Dog (Burns, Proulx, 2001)

But consider Self-Paced vs. Event-Driven environments …


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Emergency Ambulance Dispatching

• Event-driven (dynamic)• Human-human coordination

• High Social Value• Time critical• Safety critical• Large problem spaces• Uncertainty• Expertise


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Purpose

• Can Ecological Interface Design support real-time resource management in emergency ambulance dispatching?

Motivation applied: Emergency Medical Services

under strain basic: (Ecological) Interface Design for

dynamic, primarily social work domains


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• area serviced: 580 km2

• population serviced: 2.5 M (+1.5 M weekday)• 36 ambulance stations in 4 quadrants• 15-20 ambulances per quadrant at any time• ~ 12 calls per quadrant per hour, 8 responses,

5 transports• Operations: mixed fleet of ALS, BLS, ERUs• Communications: call receivers, dispatchers,

hospital destination coordinators, supervisors

Metropolitan Toronto Emergency Medical Services (TEMS)


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EMS Response

Caller Operator (911)

Call Receiver (EMS)

Dispatcher (EMS)

<= 0:45

<= 1:15Paramedics (EMS)

Alphas: <=20:59Bravos: <=10:59Charlies,

Deltas, Echos: <= 8:59

LocationProblemPriority

Unit


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Project Activities

Field Studycurrent problemscurrent solutions

Work Domain Analysis information requirements

InterfaceDesign

interfacespecifications

SimulatorNeeds

Assessment

simulatorrequirements

Interface Evaluation researchfindings

interface / simulator issues

SimulatorTesting

IntegratedTesting

InterfaceTesting


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Field Study 118 hours in communication centre

spanning 11 shifts 10 key dispatchers (0.75-20 yrs. of experience) 23 dispatch personnel in total (call receivers, other

dispatchers, hospital coordinators, 1desk)

24 hours on rideouts two 12-hour shifts ALS (19/25 yrs exp): 7 responses, 4 transports BLS: (0.75/2 yrs exp): 6 responses, 5 transports


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Information Requirements:The Decomposition Hierarchy

City Toronto

Quadrants NW, SW, NE, SE

Station Areas #10, 11, … 39

Units Ambulance Units

Emergency Response Units

Hospitals

Patients

Components Trucks, Jeeps

Paramedics

coarse

fine


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Info Req’ts: The Abstraction HierarchyRisks: patients vs Resources: ambulances

FP Threat to Public Health

(Over / Under- Utilization)

Vs Protection of Public Health

(Appropriate Utilization)

AF Death / Deterioriation

(late response,

poor resource match)

vs Survival / Improvement

(on-time response,

good resource match)

GF Priority

(alpha … echo)

Mobility

(ambulatory, stretcher-bd)

vs Response

(avail, to-scene, at-scene …)

Transport

(avail, to-dest, at-dest …)

PFu Injury / Disease

(breathing problem, fall …)

vs Skill (advanced / basic)

Transfer Capacity (stretcher?)

PFo Locations, Identities vs Locations, Identities


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Information Requirements:The Abstraction Hierarchy (cont’d)

Risks: priority posts

FP Threat to Public Health

(Effective vs. Ineffective Utilization)

AF Death / Deterioration of Potential Patients

(post coverage)

GF Post Priority

(key vs. non-key)

PFu Post

(1-16)

PFo Post Locations


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Information Availability: Summary

City Quadrants Station Areas

Units

FP x x x x

AF x x x x

GF / x

PFu

PFo


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Key Design Opportunities• Feedback at High Levels of Abstraction

– response times in relation to targets for each priority (AF-U)– resource utilization (FP-U, FP-Q/C)– resource availability (FP-Q/C)

• Feedback at High Levels of Aggregation– average response times for quadrant or city (AF-Q/C)– 90th percentile of response times for quadrant or city (AF-Q/C)

• Coverage– different levels of coverage (i.e., advanced vs. primary) for a

priority post (AF-S)– number or percentage of priority posts covered (AF-Q/C)


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Current Utilization Display(AF, All AH levels for Posts)


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Historic Utilization Display (FP)


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Current Response Times Display(AF, GF)


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Historic Response Times Display(AF)


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New Interface - Overview


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Interface Evaluation• 2 pilot subjects

– supervisors / trainers– training, practice, reduced test scenarios

• 8 “actual” subjects– 0.75-27 years as dispatcher (mean=9.8 years)– 0.75-5 years using existing interface (mean=3.3 years)

• Training session – 90 min. Tutorial + Quiz

• Practice sessions – 60 min. structured + 120 min. free-form

• Test sessions – 60 min. x 2 sessions x 2 interfaces)


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Interface EvaluationPerformance Measures

• Response Times (19 incidents over 2 scenarios)

• Assignment Times (25 incidents over 2 scenarios)

• Effectiveness – % of Deltas given Advanced Care (11 incidents over 2 scenarios)

• Efficiency – % of Alphas given Primary Care (4 incidents over 2 scenarios)

• Coverage (at PPs) (4 posts)

• Utilization– total time providing response, coverage, and patient care (2 hours)

NO significant differences between display conditions


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• For 3 of 4 displays (except CU), most participants agreed that the displays had helpful content

• For 3 of 4 displays (except CU), most participants agreed that the displays had logical structure

• For 4 of 4 displays, most participants agreed that displays were easy to use

• 7 of 8 participants would prefer to have the new displays

Interface EvaluationSubjective Ratings


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Order of Preference• Current Response Times >• Historic Utilization >• Current Utilization (Priority posts vs. Assigned units) >• Historic Response Times

NASA TLX Subjective Workload• No significant interface effect• Marginally significant order effect (p=0.07 based on

sign test) – workload higher for 2nd interface

Interface EvaluationSubjective Ratings / Rankings


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Interface EvaluationDiscussion

• Key contributors to dispatcher acceptance:– relevance to current / future decisions– relevance to own scope of authority and

responsibility

• Key barriers to dispatcher acceptance:– screen real estate– view control– potential stress

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