Modelling (16)

Question 1

Why do we model?

Answer 1

Need to know the future state of systems. For a variety of reasons (e.g., planning), we often need to know the future evolution of a system given a variety of scenarios (e.g. the flow of water in a river given soil, rain properties).

Question 2

What do planners need to make modelling assessments?

Answer 2

Planners need tools to make such an assessment. Scientists must devise approaches, and develop tools.

Question 3

How do we build forecast tools? In other words, what is the process that is referred to as system modeling?

Answer 3

1) We must determine all the factors that influence
what one is trying to forecast/influence the system;

2) We need to quantify how the interactions/influences occur
(interaction/behavior equations). These interactions
are then expressed as mathematical equations
describing how each quantity varies with time;

3) We often must estimate the initial conditions (or
starting values) of the different relevant factors;

4) We then solve these mathematical equations, which are run by computers.

Question 4

What characterizes systems with feedbacks? Give an example.

Answer 4

Systems with feedbacks often have time-dependent
behavior → Modeling requires solving for time-dependent interaction.

Example: predator and prey populations.