1.6. Overview
17
lected before we know whether we actually need it. Some of it is very
costly to collect and ultimately goes used in models , but a good guess
could have sometimes done equally well.
Computer modeling becomes "dynamic" not only when feedback
processes among system components are captured through time, but when
model development is based on the dynamic exchange of data and information among a group of model developers and users. It is the pluralism in
perspectives that helps identify key features and behaviors of complex systems, and the starting point for the generation of consensus on which recommendations for actions must ultimately be based. That pluralism is also
an important ingredient for the usefulness of models in creating new
knowledge and in providing decision support. Pluralism in perspectives is
typically not promoted or maintained to derive the solutions that outside
experts bring to a problem. We wish to encourage you to strive for this pluralism and to find in it the best answers to the questions that prompted
your modeling effort.
1.6. Overview
The process of dynamic modeling and the science of marine conservation
are each characterized by a suite of concepts, methods and tools that we
will introduce throughout the book. As we stated above , this book is divided into three parts . Part I focuses primarily on the concepts, methods
and tools for dynamic modeling and uses marine systems and marine conservation issues to illustrate the development of a dynamic model. There
are six chapters in this first part of the book. Following this introduction,
Chapter 2 presents the basic building blocks and logic used in the STELLA
programming language to develop a model of a dynamic system. Those
building blocks and logic are illustrated for hypothetical population dynamics of humpback whales . Chapter 3 expands on this model by introducing a population of prey species-the sand lance-on which whales
feed . Alongside a first glimpse into predator-prey dynamics , this chapter
also introduces the "sector" as a modeling tool to separate individual model
components and to run them in isolation of each other. So doing structures
the investigation of the dynamics of a large system and can be very useful
in confirming the appropriateness of the model structure .
Chapter 4 shows models of the spread of a disease in a population of
marine organisms. Scientists make use of modeling tools designed to facilitate explicit sequencing of events that may differ among subgroups within
the larger population to simulate the manner in which a pathogen introduced into the marine environment can rapidly spread through a population . In this chapter, you will also learn about STELLA's built-in procedures
for structured sensitivity analysis of a model and for the development of
submodels.
17
lected before we know whether we actually need it. Some of it is very
costly to collect and ultimately goes used in models , but a good guess
could have sometimes done equally well.
Computer modeling becomes "dynamic" not only when feedback
processes among system components are captured through time, but when
model development is based on the dynamic exchange of data and information among a group of model developers and users. It is the pluralism in
perspectives that helps identify key features and behaviors of complex systems, and the starting point for the generation of consensus on which recommendations for actions must ultimately be based. That pluralism is also
an important ingredient for the usefulness of models in creating new
knowledge and in providing decision support. Pluralism in perspectives is
typically not promoted or maintained to derive the solutions that outside
experts bring to a problem. We wish to encourage you to strive for this pluralism and to find in it the best answers to the questions that prompted
your modeling effort.
1.6. Overview
The process of dynamic modeling and the science of marine conservation
are each characterized by a suite of concepts, methods and tools that we
will introduce throughout the book. As we stated above , this book is divided into three parts . Part I focuses primarily on the concepts, methods
and tools for dynamic modeling and uses marine systems and marine conservation issues to illustrate the development of a dynamic model. There
are six chapters in this first part of the book. Following this introduction,
Chapter 2 presents the basic building blocks and logic used in the STELLA
programming language to develop a model of a dynamic system. Those
building blocks and logic are illustrated for hypothetical population dynamics of humpback whales . Chapter 3 expands on this model by introducing a population of prey species-the sand lance-on which whales
feed . Alongside a first glimpse into predator-prey dynamics , this chapter
also introduces the "sector" as a modeling tool to separate individual model
components and to run them in isolation of each other. So doing structures
the investigation of the dynamics of a large system and can be very useful
in confirming the appropriateness of the model structure .
Chapter 4 shows models of the spread of a disease in a population of
marine organisms. Scientists make use of modeling tools designed to facilitate explicit sequencing of events that may differ among subgroups within
the larger population to simulate the manner in which a pathogen introduced into the marine environment can rapidly spread through a population . In this chapter, you will also learn about STELLA's built-in procedures
for structured sensitivity analysis of a model and for the development of
submodels.