2.5 Modeling a System

Many things in the real world are complex and dynamic and hard to understand. In such
cases, we use a mechanism called modeling to simplify presentation of such things. It is then
easier to understand, to test their effects and different relationships.

A model can be described as an abstraction or approximation that is used to represent
reality. Good models enable us to explore and gain improved understanding of real-world
situations. This is not a new technique. Even ancient people had used diagrams as models to
present things.

Examples of models:

A written description of a battle
A physical mock-up of an ancient building
The use of symbols to represent money, numbers
Mathematical relationships

Today, scientists, engineers, managers and other professionals use different models to
understand complex problems and to present different solutions. In the context of
organizations, managers and decision makers use models to help them understand what is
happening in their organizations and make better decisions.
In general, models can be classified into various types as narrative, physical, schematic and mathematical.

Narrative Model:
A narrative model is based on words, spoken or written.
Both verbal and written descriptions of reality are considered narrative models.
In an organization, reports, documents and conversations concerning a system are all
important narratives

Computers can be used to develop narrative models.

Example: word processing

Physical Model:
A physical model is a tangible representation of reality.
Many physical models are computer designed or constructed.

Schematic Model:
A schematic model is a graphical representation of reality.
Graphs, charts, figures, diagrams, illustrations, and pictures are all types of schematic models.
Schematic models are used extensively in developing computer programs and systems.

Mathematical Model:
A mathematical model is an arithmetic representation of reality. Computers excel at solving
mathematical models.

Examples:

Retail chains have developed mathematical models to identify all the activities, effort, and
time associated with planning, building, and opening a new store so that they can forecast
how long it will take to complete a store.

A mathematical model developed to determine the total cost of a project.

TC = (V)(X) + FC where
TC = total cost
V = variable cost per unit
X = number of units produced
FC = fixed cost

When a model is developed, it is important to maintain its accuracy to use the model
effectively for problem solving. Otherwise the solutions obtained through the model may not
be valid. Models are usually based on assumptions and if they are not realistic assumptions, it
leads to inaccuracy. Therefore, the potential users should clearly understand these
assumptions.