The Pursuit of Understanding: Modelling Dynamic Behaviour in ...

THE PURSUIT OF UNDERSTANDING: MODELLING DYNAMIC BEHAVIOUR IN DISEASE, LIFE & LOVE Brian Dangerfield Professor of Systems Modelling Centre for OR & Applied Statistics System Dynamics

modelling is based upon: * Concept of Information Feedback * Delays * Mapping Tools Stock-Flow Diagrams Influence Diagrams * Equations linking variables to one

another in the system Chou En-lai (1898-1976) - asked for his assessment of the effects of the French Revolution At what minute did most people enter the bar?

At what minute did most people leave the bar? At what minute were most people in the bar? At what minute were fewest people in the bar? A stock-flow diagram

Entering In the bar Leaving COCAINE PREVALENCE IN THE USA

Survey data suggested lifetime prevalence estimates .were falling rapidly in the latter part of 1980s Argument for more resources to support policies of .interdiction & incarceration (rather than prevention) ;But reported decline physically impossible (Homer) Survey collected biased data- first time

cocaine use Current & Past Users (lifetime prevalence) death from

all causes Limits on Our Capacity for Processing Information 7 +2 George Miller, Psychological Review 63:2 (1956) pp. 81-97

5 variables A, B, C, D, and E A A= f (B,C,D) B= f (C, E) C= f (B,A)

B C D= f (C, E) E= f (B,C) E

D Who are the most important people involved in securing the safe passage of an aircraft from A to B?

DYNAMICS OF AN EPIDEMIC MILESTONES IN THE EVOLUTION OF THE HIV/AIDS MODEL Number of Feature

equations (approx) Year (quarter) of introduction Project-based model 13

1987(2) Variable infectivity 20 1989(1)

Heterogeneity & changing behaviour 47 1990(2) Reporting delay & fitting model to data

70 1992(2) Treatment effect & removals / additions 120

1997(4) Health care sector 190 1998(4)

Introduction of HAART 300 1999(2) 360

2001(3) Effects of regression in behaviour after HAART (fitting to HIV data) Estimated Numbers & Percent on HAART at end-1998

Homo/bisexual men only Estimated Number of Patients U.K. 10734 France 17500 Germany

10359 Netherlands 2069 Percent of total 67% 64% 69%

76% FASHION ITEM DYNAMICS TOURIST DEVELOPMENT IN ISLAND ECONOMIES SUSTAINABLE DEVELOPMENT IN

AN ISLAND TOURIST ECONOMY Need a balance between economic gain and environmental conservation. For: jobs; tax revenue; foreign currency earnings Against: environmental pollution; higher cost of living; migration from agriculture to tourist services

Environmental deterioration might affect the numbers and/or mix of tourist visitors no rail links - congested motorways Reina Sofia airport congestion obsolete tourist facilities; poor professional training Issues:

water supply waste collection and treatment communications health care noise pollution public safety DIFFUSION OF AN INNOVATION

Barriers to innovation: QWERTY Keyboard : Sholes vs Dvorak VHS video format vs Betamax Sharp take-off innovations: CAT scanners Mobile phones

CLUBBED TO DEATH (Student Direct Dec. 2002) Superclubs are suffering Renaissance; Gatecrasher, Cream. How did things go so wrong? Competition more clubs and (now) bars. Merchandising (In 2000, 5% of MoS

profits came from the clubs). Big name DJs charged at least 10K per set. Higher door prices. spin-off merchandising 2 (brand awareness)

+ + + 1 visiting rate + profits + +

numbers in club per club per week - 6 3 new bar + 4

openings + + new club DJ fees openings average club

5 door price+ SARAWAK (EAST MALAYSIA) CORAS/CER Two year research project Economic model for the State Government

Model Purpose? Map of Borneo GDP RM Millions Sarawak Gross Domestic Product 1980 1999

(Constant Prices) 14,000 12,000 10,000 8,000 6,000 4,000

2,000 0 1980 1983 1986

1989 Years 1992 1995 1998

DYNAMIC HYPOTHESIS: high-level map SUPPLY Primary & Secondary Education Federal

Funds DEMAND Primary Industry (Agric; Forestry; Mining; M/facturing) Secondary Industry

(Transport; Storage; Retail; Finance & Insurance) F D I

Knowledge-based Industry & Services High Value-added; Biotech; Medicine Higher Education (Arts)

Leakage Overseas ? Higher Education (Science)

Skills/Tech Transfer Money Capital Equipment Human Resources R&D Centres

(Exemplars) Vocational Education (Sub-professional) State Revenue

State Incentives Closures? COMMS INFRASTRUCTURE

ICT Infrastructure Broadband Cabling (Kms) Number of

PCs + - K. Industries+

+ ICT Resources + (actual) + R&D Centres +

+ ICT Resources + (desired) + Supply of High-Tech Human

Capital - Virtuous circles (positive loops): if ICT Resources (actual)>= ICT Resources (desired). Otherwise negative loops come into play & positive loops shifted from growth to decay mode

DYNAMICS OF A PARTNERSHIP Sustainable Futures: Endgames: Sustainable Futures: Golden Wedding

+ 0 - Time

Sustainable Futures: Amo et Odi + 0 -

Time Endgames: Were still good friends + 0

- Time Endgames: Mutual loathing +

0 - Time EU Divorce Rates in 2001 (per '000 population)

EU Divorce Rates in 2001 (per '000 population) 3.5 3 2.5 2 1.5 1 0.5

0 2.6 2.7 2 2.6 2.9

1.9 0.9 1 0.7 0.7 UK Marriages

500000 406000 400000 286000

300000 200000 100000 0 1976 2001

England & Wales Divorce Rates per '000 Married Population 15.00 10.00 5.00 0.00 1976