Economic models

Economics and Theory
Economic Models
Watches as Models of Time
Donald Elliott, Southern Illinois University Edwardsville
How to introduce the concept of a "model" its purpose and evaluation. Hold up your watch. Ask: (a) Is a watch a model? (Yes) (b) Of what? (The passage of time.) (c) Must the watch duplicate the actual process of the passage of time? (Of course not; it simplifies thiscomplex process by providing an acceptable representation of the process.) (d) Is there a unique model? (No; consider the many different mechanisms used in watches to stimulate this process springs and balance wheels, tuning forks, quartz crystals, etc.) (e) How can one evaluate the relative performance of different models? (If the models (watches) yield different predictions (times) over some periodof observation, they can be evaluated relative to some benchmark which is considered to represent reality.)
Realism in Airplane Models
Regan Whitworth, American University of Armenia
Bring to class in separate boxes an elaborate plastic model airplane and a balsa glider. Display the plastic model to the class, pointing out all the "realistic" features of the model: gray color, rivets, visibleseams between plates, markings, etc. Then point out that it's really NOT realistic: it's made of plastic, not metal; has no seats; is not big enough to get into; and moreover, it won't do the one thing which airplanes must do: FLY!!! Remove balsa model from box. Point out that this model, which many people would regard as much less realistic, will fly. A demonstration is sometimes a usefuldiversion.
It can then be pointed out that no model is realistic, in the sense that it can't do everything the original does, or it wouldn't be a model. The kind of model one chooses depends on what one is trying to find out. Both models have their uses, but neither is "realistic" if put to the wrong use.
What Is an Abstraction or Model?
Herbert M. Bernstein, Drexel University
To emphasize the needfor abstracting or constructing a model when explaining economic relationships, I draw a crude face on the board.

Figure 1 1
I ask what the drawing is, and students respond that it is a face. I ask them to describe this face, and if they have ever met anyone who looks like this caricature. The point is made that they do not need a Rembrandt depiction to ascertain certain information and thatrelevance, rather than realism, is the essence of theorizing.
Models of Prospective Spouses
Joe A. Garwood, Valencia Community College
Early in the Principles course we all usually deal with the concept of abstracting and its importance to economics. We need to do this to show why it's necessary to abstract, and to allay student apprehensions about our simplified examples and heavy use ofmodels, theories, principles, etc.
I ask a student whom I know to be single whether or not he or she ever intends to marry. If the answer is yes, I point out that there are roughly three billion people of the opposite sex to choose from and that finding "Mr. or Ms. Right" could be quite a chore. I then ask how the student intends to go about finding the ideal mate. In response, the student willindicate that certain criteria are used to reduce the sample to manageable proportions, e.g., appearance, education, location, personality, religion, or special interests.
After going through this process I point out that the student has been abstracting and emphasize how necessary it is to the final outcome. I also point out that the criteria used represent theories about what will make the idealmate for that student. Conclusion abstractions and theories are absolutely essential if we are to make any sense out of the real world. This is a real interest grabber and it develops an appreciation for the need to abstract.
Introducing the Concept of Economic Models
Rose M. Rubin, University of North Texas
Students often have difficulty initially grasping the concepts of modeling and of...