SYSTEM DYNAMICS COMPUTER SIMULATION MODEL OF
CROATIA
ANTE MUNITIC
MARINE FACULTY DUBROVNIK
UNIVERSITY OF SPLIT
CROATIA
ABSTRACT
The proposed model is a scientific attempt to apply the
methodology of System Dynamics to research one of the most complex
organization system of management, withthe aim of finding out the most
suitable scenario of the mangement by economic migration flows. The
problem of economic migration is one of the most important problems
both for the countries of origin and for the receiving countries.
Computer simulation of the proposed model confirms most of the results
achieved by Andre Sapir, but pointing to the possibility of multilateral
consultation of the managers of the regional system, as well as of the
society to which it belongs, in this case : REPUBLICA of CROATIA, and
the managers of the countries which absorb the economic migrations
flows. The result of these multilateral consultations would be very useful
for the countries of origin, and for the countries that receive economic
migrants as well !
1. INTRODUCTION
It is generally believed that economic migrations bring
profit to the receiving countries, while they have negative effect on the
countries of origin ! In the case of REPUBLICA of CROATIA, however,
as the regional system of YUGOSLAVIA, economic migrations have, in
spite of numerous negative effects, contributed to the development of
CROATIA, respectively YUCOSLAVIA as a whole, after the World War
Ih.
It is possible to meet the interests of those countries of
origin of economic migrants on which the migrations had negative
effects, and even to assure their future development ! Such countries
must change from countries of origin to the countries which receive their
own migrants, in the following way :
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System Dynamics '91 Page 387
1, Receiving countries and countries of origin of economic
migrants must jointly plan the input and output flow of migrants in
accordance with “foreseen” trade prosperity movements of the world
market !
2. The country of origin will, in the feedback cycle of the
migrations flows, change to the country which receives its own
economic migrants (returned economic migrants) !
It will in this way, with the help of the developed
countries that had up to that point been using its migrations flows,
realise the conditions for its own progressive development.
The System Dynamics Computer Simulation Model. of the
flows of populations, economic migrants, financial investment
capital, economic migrants policy, economic and social development of a
relatively “developed” : REPUBLICA of CROATIA, as a part of
YUGOSLAVIA, is proposed in order to facilitate the multilateral
negotiations between REPUBLICA of CROATIA, YUGOSLAVIA and THE
REST OF THE WORLD.
2. BASIC CHARACTERISTICS OF THE RECIONAL SOCIO-ECONOMIC
SYSTEM OF REPUBLICA OF CROATIA
By regional socio-economic system in Yugoslavia is meant
*Territorial-geographical and analytical-planning frame for mutual
solving of the common needs of associated communes.”, in this project
called : CROATIA ! Owing to the knowledge and methodology of the
following scientific disciplines : The General Theory. of Systems, The
General Theory of Management, The Theory of Information, The System
Dynamics, The Colbal Theory of Organization, The Theory of
Reproduction of Socio-Economic Systems, and The Theory of Chaos, it
is possible to represent REPUBLICA of CROATIA with "rudimentary
model of cause-consequences communication canals which flowing by
material, energy and information flows , link between three systems:
CROATIA, YUCOSLAVIA (VDES) and THE REST OF THE WORLD
(VDEIS-ihe remaining world to which economic migrations of CROATIA
tend to flow )!
Page 388 System Dynamics '91
REPUBLICA of CROATIA is, at the same time, a
subsystem of YUGOSLAVIA (the country to which it belongs), and THE
REST OF THE WORLD (of the developed countries-the remaining world
to which economic migrations of CROATIA tend to flow )!
CROATIA YUCOSLAVIA THE REST OF THE
(RDES) (VDES) WORLD
Figure 1. Rudimentary model of material, energy and information
communication canals of CROATIA
The directed full-curves represent at least one flow of
matter or information, in this case : economic migrants, financial capital,
information of trade prosperity e.t.c..
Let it be :
-MZS -Material Standard of Living of CROATIA
(national income per capita, $/person-year)
-MZSO-Material Standard of Living of YUCOSLAVIA
(national income per capita, $/person-year)
-MZSI-Material Standard of Living of THE REST OF
THE WORLD (national income per capita, $/
person-year)
-RNPR-The Level of the Economic Migrants of
CROATIA in THE REST OF THE WORLD
(persons)
-RPORO-Resirictive Policy of The Employing
Possibility for Economic Migrants of YUCOSLA-
VIA in CROATIA (mechanical inflow)
(dimensionless)
-RPORI-Restrictive Policy of The Employing
Possibility for Economic Migrants of CROATIA
in THE REST OF THE WORLD (dimensionless)
It is possible to present the structurakcausal model of
System Dynamics '91 Page 389
CROATIA by these cause-consequences links between level and rate
variables (Figure 2.):
RPORO influence on the
economic productivity
of CROATIA . Fe
FBL3.(+) P
social income of
MZSO CROATIA:
ADN
noneconomic activity
of CROATIA
PIVDES
investment policy
of YUGOSLAVIA in
CROATIA internal migration
balance of CROATIA
+
FBL 2.(+)
+
MZS
material standard
of living of
FBL7.(-) CROATIA
FBL6.(-)
PIVDEIS FBL1.(-)
investment policy of
THE REST OF THE
in CROATIA _ toy
BNPR ——————_____-~"N STA
+ \ Cie of CROATIA
FBL8.(-)
MZSI es
DRZORM
financial capital of the
RPORI economic migrants in
CROATIA
Figure 2. The structural model of CROATIA
Page 390 System Dynamics '91
FBL1. This feedhack loop has a self-managing character,
or “negative” sign, because in the FBL1. exists next couse-consequence
links : ” If the MZS- material standard of living increases then
STA-population will increase too, and sign of this cause -consequence
link is plus (+)”. And, ” if STA-population. of CROATIA increases then
MZS-material standard of living will decrease, and sign of this cause
-consequence linkis “negative” (-) *. The global sign of the FBL1. is
“negative”, or its character is selfmanaging, because FBL1. has odd
number of “negative” signs !
FBL2. The global dynamics character of this feedback loop
is “positive”. It means : exponential increase or decrease character,
because in this feedback loop exist those cause-consequnces links : ” If
DP social income increases than M2ZS-material standard of living
(national income per capita) willincrease too. And, if M2ZS-material
standard of living increases that DP-social income will increase too.” ! In
this case, this feedback loop has not any dynamics character
cause-consequnces links with “negative” sign and- result is global
“positive” sign of the FBL2. .
FBL3, The global dynamics character of this feedback loop
is same as FBL2., because in this feedback loop exists next
cause-consequnces links : ” If MZS-material standard of living increases
then ADN-noneconomic activity (or social activity) will increase too. It
means: “positive” sign of this cause-consequnces link! And, if
ADN-noneconomic or social activity increases then PIP-noneconomic
activity influence on the economic productivityof CROATIA will increase
too, and dynamics character of this link is also “positive”. Further, if
PIP-noneconomic or social activity influence on the economic productivity
increases then DP-social income will increase too, and it means, that this
link has “positive” dynamics character. And, if. DP-social income
increases then MZS-material standard of living willincrease too, and
dynamics character of this link will also be “positive’” We could see
that FBL3. has not any “negative” dynamics character
cause-consequences links, and direct effect is : “positive” dynamics
character of the FBL3.!
FBL4. This feedback loop represents an “internal
migrations balance” of CROATIA, and so, it has special importance,
because CROATIA is very interesting for the population of the “rest of
Yugoslavia” (economic emigration flow -"mehanical inflow’ ). In this
System Dynamics '91 Page 391
feedback loop exists following cause-consequnces consideration holds
good : “If the MZSO-material standard of living of YUGOSLAVIA
increases then the UMS-internal migration balance of CROATIA will
decrease, because “mechanical inflow” from the rest of YUGOSLAVIA
could be decrease. This means, that dynamics character of this
cause-consequence link has “negative” sign. Further, if
RPORO-restrictive policy of the employing possibility for economic
migrants of YUGOSLAVIA (VDES) in CROATIA increases then the
UMS-internal migration balance will increase too, it means :”positive”
sign of this link. At same case, if the UMS-internal migration balance of
CROATIA increases then also the STA-global level of population will
increase, it means, that this link has “positive” dynamics character. And,
if STA-global level of population of CROATIA increases then the
UMS-internal migrations balance of CROATIA will decrease, it means,
that this link has “negative” sign. The global dynamics sign of the
FBL4. is “negative”, it means, that FBL4 has “selfmanaging dynamics
character”.”!
FBL5. This feedback loop represents an external
migrations balance, or exactly : RNPR-level of economic emigrant
workers of CROATIA on temporary work in THE REST OF THE
WORLD (VDEIS), and it is very important for CROATIA t RNPR-level
of economic emigrant workers of CROATIA on temporary work has
greatly contributed to the development of CROATIA, in the post-II
World War period. The FBL5. has also “self-managing” character, or
“negative” global sign. This dynamics character is result existing of the
next cause-consequnces links :” If the RNPR-level of economic emigrant
workers on temporarily work in THE REST OF THE WORLD increases
then STA-global level of population of CROATIA will decrease, and it
means: “negative” dynamics character of this link. Further, if
STA-global level of population of CROATIA increases then RNPR will
increase too, and it means ;:”positive’ dynamics character of this
cause-consequences link, or “positive” sign” ! The global dynamics
character of FBL5. is “negative”,or “selfmanaging”, because it has odd
number of “negative” signs.
FBL6. This feedback loop is very important for
socio-economic development of CROATIA, because it has
self managing” or “self regulation”dynamics character, and in this
feedback loop exists the next cause-consequnces links : ie ba
MZS-material standard of living of CROATIA increases then ADN-social
Page 392 System Dynamics '91
activity of CROATIA willincrease too, and this means : “positive”
dynamics character of this link. Further, if ADN-social activity of
CROATIA increases then STA-global level of population of CROATIA will
increase also, ‘and we see that dynamics character of this
cause-consequnces link is “positive”. And, if STA-global level of
population increases then MZS-material standard of living of CROATIA
(national income per capita) will decrease, and the dynamics character of
this cause-consequnces link is “negative” or .”self-managing”!”. In any
case,the global. dynamic character of FBL6. is “negative” or
“self-managing” or “self-regulation”, because FBL6. has odd number of
“negative” signs.
FBL7. This feedback loop has “self-managing”, or
”self-regulation” dynamics character, also as FBL6., because it has next
cause-consequences links : ” If the MZS-material standard of living
increases then RNPR-level of economic emigrants workers of CROATIA
on temporary works in THE REST OF THE WORLD will decrease, and
it means :”negative” sign of this cause-consequences link. Further, if
RNPR-variable increases then STA-global level of population of CROATIA
will decrease, and it means :"negative” sign of this cause-consequnces
link, and, if STA-global level of population of CROATIA increases then
the MZS-material standard of living will. decrease, and it means also
“negative” sign of this cause-consequnces. link.”! Because FBLT. has
odd number (3) of “negative” signs then FBL7. has also “negative”
sign, or "self-managing” or “self-regulating” dynamics character!
FBL8.. The FBL8. has also "self-managing” or
“self-regulation” dynamics character, because in it exists next
cause-consequnces links : ” If the RNPR-migrant workers of the
CROATIA on temporary work in THE REST OF THE WORLD increases
then DRZORM-investment capital, or worker remittance, of the abroad
economic migrants will also increase, and dynamic character of this
cause-consequnces link is positive”, and, if DRZORM- variable
increases then DP-social income of CROATIA will also increase, which it
means also “positive” sign of this. link. Further, if DP-social income of
CROATIA increases then MZS-material standard of living of CROATIA
will increase too, and it means also positive” sign of this link. And, if
MZS-material standard of living. of CROATIA increases then
RNPR-variable willdecrease, and this last cause-consequnces link has
“negative” sign.”! The global sign of. FBL8. is “negative” , or
”self-managing” too, because it has odd number of “negative” dynamics
System Dynamics '91 Page 393
character links!
Also, it is very important to tell that YUCOSLAVIA
(VDES) and THE REST OF THE WORLD (VDEIS) have had special
investment policy’ for social-economic developing - of . REPUBLICA
CROATIA (RDES). For this reason, in this model, there are. two
variables : PIVDES-investment policy of YUCOSLAVIA (VDES) in. the
CROATIA, and PIVDEIS-investment policy of THE REST OF THE
WORLD (VDEIS) in the CROATIA ! Both have same dynamics character
: “positive”, because their increase has for influence also increased the
DP-social income of CROATIA t
3. CONSEQUENCE : “SYSTEM DYNAMICS COMPUTER SIMULATION
MODEL OF CROATIA”
On this ” system dynamics way ”, and, in the same time,
in the accordance with System Dynamics knowledge and experiences, the
autor of this paper has worked out two : “System Dynamics Computer
Simulation Model of CROATIA” :
1. ™"MRDES”-first simpler, with only 131 main equations
(the author had represented this model on _ the
INTERNATI- ONAL SYSTEM DYNAMICS CONFERENCE
1988, San Diego, California, La Jolla, July 5-8), and
2.” PSMURPI”-second complex, with more than 655 equ-
ations (he autor worked out this model at the beginning
of 1991.).
*MRDES” is composted of the 9 sectors :
- POPULATION,
. GLOBAL MIGRATION BALANCE,
. WORKINGACTIVE POPULATION,
. LABOUR,
. LABOUR ON THE TEMPORARY WORK,
. ECONOMIC AND NONECONOMIC PRODUCTION CAPA-
CITIES,
1. SOCIAL AND NATIONAL INCOME,
au toat =
Page 394 System Dynamics '91
8. REPRODUCTION FUNDS,
9. INFLUENCE OF ENVIRONMENT (VDES AND VDEIS).
*PSMURPI” is composed of 4 parallel
* MRADES” submodels, because REPUBLICA of CROATIA as a whole,
has 4 Regional Socio-Economic System, or 4 regions, and summary
model of CROATIA.
*MRDES” and "PSMURPI” has one special MACRO
function for computing "average growth rate” of any variable, in (96),
and it has next model in DYNAMO :
MACRO PGSRV(X,DELP)
INTRN DELX,SLOPE
L DELX.K-DELX.J+(DT/DELP)x (X.K-DELX-K)
N DELX-X
A SLOPE.K-(X.K-DELX.K)/DELP
A PGSRV.K-(SLOPE.K/DELX.K)=100
MEND
In any case, DELP-average time period, and modeller has
a possibility to take any number of elementary time period !
*MRDES” and "PSMURPI” have two worked out software
versions :
1. in "SYSDYNS” ( autor is Dr. Ante Munitic), which has
for operative base : QUICK BASIC (QB) language, and
2. in "PROFESSIONAL DYNAMO PLUS” (PDP) |
4. INSTEAD CONCLUSIONS
*MRDES” and “PSMURPI” have instaled in STATE
INSTITUTION OF REPUBLICA OF CROATIA (Project : ” SYSTEM
DYNAMICS COMPUTER SIMULATION MODEL OF CROATIA”),
and theirs author is ready to represent them on PC ,to anybody interested
in it, if he could, and what he could have too!
System Dynamics '91 Page 395
5. REFERENCES
Dr. Ante Munitic : KOMPJUTERSKA SIMULACIJA UZ POMOC
SISTEMSKE DINAMIKE, Muzej BRODOSPLIT, 1990.,
PARALELE/Tiskarna Ljubljana, Slovenija, Yugoslavia
Dr. Milos Rajkov : TEORIJA DINAMIKE ORCANIZACIONIH I
EKONOMSKIH SISTEMA, Kultura,1988., Knjizevno-
-izdavacka zadruga Beograd, Srbija, Yugoslavia
Dr. Jay W. Forrester : WORLD DYNAMICS ,Wright-Allen Press, Inc.,
Cambridge, Massachusetts, U.S.A., 1971,1973
Dennis L. Meadows, William W. Behrens III, Donélla H. Meadows,
Roger F. Naill, Jorgen Randers, Erich K.O. Zahn : DYNAMICS OF
GROWTH IN A FINITE WORLD, Wright-Allen Press, Inc.,
Cambridge, Massachusetts, U.S.A., 1974.
Dr. George P. Richardson, Aleksander L. Pugh III : INTRODUCTION TO
SYSTEM DYNAMICS MODELING with DYNAMO, The M.T.I.
Press, Cambridge, Massachusetts, U.S.A., 1981.
Dr. Mladen Friganovic : DEMOGRAFIJA-STANOVNISTVO = SVIJETA,
Skolska knjiga - Zagreb, 1978., Yugoslavia
Dr. Joseph A. Schumpeter : POVIJEST EKONOMSKE ANALIZE I I II,
Informator-Zagreb, 1975., C Oxford University Press, Inc.,
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Dr. Ante Munitic : MODEL OF ONE REGIONAL SELFMANAGING
SOCIALIST SOCIO-ECONOMIC SYSTEM, International
System Dynamics Conference 1988., San Diego, Califor-
nia, U.S.A.
Dr. Ante Munitic : MODEL RECIONALNOG DRUSTVENO-EKONOMSKOCG
SISTEMA, doktorska disertacija, 1983., Fakultet organiza-
cionih nauka, Beograd, Srbija, Yugoslavia
Dr. Andre Sapir : "ECONOMIC REFORM AND MICRATION IN YUGO-
SLAVIA”, An Econometric Model, Journal of Development
Economics Vol. 9, (1981) 149-181, North-Holland. Publish-
ing Company, 1981
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