Bunche Hall

CAI Efforts in the Department of Economics CAI with Java and CGI Forms

ECONOMICS 1:  Introduction to the Principles of Microeconomics

1. Consumer Choice-Utility Maximization Subject to a Budget Constraint
URL: http://econtools.com/jevons/java/choice/Choice.html

This applet provides a visual demonstration of utility maximization subject to a budget constraint. Itshows how the utility-maximizing consumption choice varies as prices change.  A second, related applet shows how these choices can trace out a demand curve.

The Linear Demand, Elasticity, and Total Revenue applet allows students to change demand equation parameters. Dragging the price or quantity sliders lets the student see the relationships between the demand curve, elasticity, and the amount of total revenue.

This applet illustrates the short run profit maximizing decision that a Competitive Firm faces for various prices.  The student adjusts prices by dragging a slider.  In response, the applet gives the profit maximizing quantity and the resulting profit rectangle that the price-taking firm would choose.  The applet also illustrates the short run shutdown decision: choosing a zero quantity when the price drops below average variable cost.

A more recent applet is an Edgeworth box with Cobb-Douglas utility maximizers.   This applet is able to demonstrate the Core, the Pareto optimal contract curve,  the Walrasian equilibrium, the lens-shaped area comprising individually rational choices, and prices for different endowments and preferences. The code that underlies this applet is written from the perspective of a game-theoretic economist, where the players are objects with defined traits.  The applet is introduced through a Guided Tour, and Cameron has also written an interactive quiz that walks a student through the use of the applet while describing the difference between the concepts of equity and efficiency.

Using a framework developed by Gerdes, Cameron has created a series of online self-grading quizzes.

ECONOMICS 143:  Applied Regression Analysis

1. Student's t Distribution
URL: http://econtools.com/jevons/java/Graphics2D/tDist.html

This applet shows the shape of the student t distribution and how it compares to the standard normal distribution.  As the student drags the slider to change the degrees of freedom, the relative shapes of the curves change and the cut off values for a 5 percent level of confidence are shown for both distributions.

This applet shows the shape of the F distribution and the cut off value for 5 percent confidence.  The student can adjust the degrees of freedom for both the numerator and the denominator.

 The 2D Function Studio applet is a multiple-windowed framework for the display of any general two dimensional function and its properties.  This applet allows the user to adjust the values of various parameters on the right- hand side of the equation, and immediately see the resulting curve in the graph.  With one drag of a slider, the function smoothly evolves right before the student's eyes.  In addition, the student may choose to display the derivative of the function in the same graph and watch how it evolves as well.  Additional functionality can also be added as well, such as the highlighting of local mins and maxes, etc.

 

Student use of this applet is aided, once again, by a Guided Tour of the key control panel elements.  A lab  also takes students through the use of the applet, and a self-grading quiz has been prepared to illustrate the ideas behind quadratic forms in regression analysis. This applet is capable of accepting an unlimited number of additional functions with their derivatives and default settings pre-defined with a trivial amount of additional programming for each new definition.  In fact, if it is deemed useful, the applet could also be made to accept a user's own compiled function class (based on a prototype with instructions) without the need to re-compile or release the source code of the display applet itself.  Thus, instructors with a limited knowledge of java programming would nevertheless be able to independently add their own functions as they see fit!

Using a framework developed by Gerdes, Cameron has created a series of online self-grading quizzes.

For some purposes, applets can be found on the Web that do a  good enough  job such that development of entirely new applets is probably not warranted.  For example, the authors have found publicly available source code for a three-dimensional plotting applet, located at  http://www.sscnet.ucla.edu/ssc/labs/cameron/java/SurfacePlotter.  The author of the code has graciously agreed to allow us to use it.  Given the highly developed state of this applet, it is probably not cost-effective at this time to develop a new more-specialized three-dimensional plotting program.  Although the plotting options in this existing program are somewhat limited, and the ideal applet would have different features, it is possible to  make do  with this program in the near term.  In other cases, no currently available applet can be found to fill our needs.  In the case of the functionStudio applet, listed above for Economics 143, there was no existing applet that would meet the identified pedagogical requirements.  Over time, we expect that the number of useful applets on the web will grow.

ECONOMICS 146:  Linear Models in Economics

This CGI form is a simple interface to a public domain linear program solver called lp_solve.  The interface is written in Perl, and the lp_solve program itself is a compiled c program.  Students were invited to use the interface to solve homework problems.

This applet gives more elaborate feedback to students by outputting the sequence of tableaus that would be used to solve a linear program using the Simplex method.  This program was written entirely from scratch in C++, but used some classes provided with the gnu C++ library.

Graduate student Mike Beauregard has created a five-year archive of syllabi from past Department of Economics courses to help students choose courses of interest.