Examples of Models
Figure 1. A architectural model.
An architect who is designing a major office building will probably build a physical model that sits on a tabletop to show how the entire city block will look after the new building is constructed. Companies often build models of their new products that are rougher and less finished than the final product but can still demonstrate how the new product will work and look. Such models help people visualize a product (or a building) in a more complete, concrete way than they could without them.
Similarly, economic models offer a way to get a complete view or picture of an economic situation and understand how economic factors fit together.
A good model to start with in economics is the circular flow diagram (Figure 2, below). Such a diagram indicates that the economy consists of two groups, households and firms, which interact in two markets: the goods-and-services market (also called the product market), in which firms sell and households buy, and the labor market, in which households sell labor to business firms or other employees.
Figure 2. The Circular Flow Diagram.
Of course, in the real world, there are many different markets for goods and services and markets for many different types of labor. The circular flow diagram simplifies these distinctions in order to make the picture easier to grasp. In the diagram, firms produce goods and services, which they sell to households in return for payments. The outer ring represents the two sides of the product market (which provides goods and services), in which households demand and firms supply. In addition, households (as workers) sell their labor to firms in return for wages, salaries, and benefits. This is shown in the inner circle, which represents the two sides of the labor market, in which households supply and firms demand. This version of the circular flow model is stripped down to the essentials, but it has enough features to explain how the product and labor markets work in the economy.
We could easily add details to this basic model if we wanted to introduce more real-world elements, like financial markets, governments, or interactions with the rest of the world (imports and exports). Economists reach for theories in much the same way as a carpenter might grab a tool. When economists identify an economic issue or problem, they sift through the available theories to see if they can find one that fits. Then they use the theory to give them insights about the issue or problem. In economics, theories are expressed in models as diagrams, graphs, or even as mathematical equations. Counter to what you might expect, economists don't figure out the solution to a problem and then draw the graph. Instead, they use the graph to help them discover the answer. In this way, these graphs serve as models to make inferences about behavior.
At the introductory level, you can sometimes figure out the right answer without using a model, but if you keep studying economics, before too long you'll encounter issues and problems whose solution will require graphs. Both micro and macroeconomics are explained in terms of theories and models. The most well-known theories are probably those of supply and demand, but you will learn about several others.