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Presentation 7A2. VESTAC: Applets for Experimenting with Statistical Concepts

Paul Darius (Belgium)


Presentation Abstract

Teachers of statistics encounter a number of didactic problems, especially when teaching the introductory statistics course. It has been argued in the literature that supplementing the traditional material with tools based on a visual approach and a more active form of learning, could improve the effectiveness of the teaching.

This paper describes such a tool. It consists of a set of JAVA applets called VESTAC (Visualization of and Experimentation with STAtistical Concepts), covering selected topics useful for an introductory course and a second regression and/or anova course. Each applet gives a visual representation of the topic, with ample possibilities to see the asymptotic results build up, or to experiment with the data and the parameters and see the effects immediately. Those topics were selected where it was thought that an interactive visual applet could have didactic properties exceeding those attainable with more traditional didactic tools.

The VESTAC collection currently consists of 32 applets. Additional ones are under construction. They cover selected topics from the following four areas: distributions and plots, tests and confidence intervals, regression and analysis of variance.

Although several interactive tools for statistical teaching have been described in the literature or are available at several places on the Internet, the VESTAC collection is rather different in a number of important aspects.

First of all, every effort has been made to give the applets, as much as possible, a common "look and feel". The collection is based on an extensive class library specially written in JAVA to implement certain GUI aspects, repeated random simulation, construction of statistical graphs and statistical computation. All the applets use classes from this library.

An applet originally appears in a separate window, with default parameter settings applied. This makes it possible to start the applet demonstration quickly (e.g. while teaching in a classroom). The visual elements (e.g. the points on a scatterplot) can, wherever applicable, be manipulated directly by dragging with the mouse. The most important parameters (e.g. the degrees of freedom of a distribution) can be adjusted directly on the screen. All the other parameters can be changed through a pop-up window. The applets not only execute simulation based on settings of population parameters, those for which it is relevant also allow import of an actual dataset. This makes it possible for the applets to use the same datasets as e.g. those in the textbook.

The most interesting learning experience occurs when two or more parameter settings can be compared side by side. To make this possible, all the applets have the following features: upon hitting a "new window" button, a new window appears and the previous windows are resized, so that they are all visible on the screen. Each window now behaves a s a separate applet: parameters can be changed on each and computations in each window occur concurrently.

The VESTAC applets are intended for use by the teacher in the classroom, as well as for supervised use by students during practical exercises in a PC classroom, and for unsupervised use by students at home. They are currently used in a variety of courses at the authors' universities, as well as in some others.


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