### Gallery of Applets

Welcome to the gallery of BolderStats applets. These Java applets were prepared for instructional use in statistics classes at the University of Colorado. They are not intended for statistical calcuations. Instead, they illustrate various statistical principles. Direct interaction with the applets allows students to better understand the underlying statistical principles.

All applets demonstrated here use the charting, mathematical, and statistical class files of Visual Numerics' JMSL™ Numerical Library for Java™ Applications. If you have any trouble with the applets, check Browser Notes for tested browsers and operating systems as well as necessary plug-ins.

Click on the links to the left to see each applet. The page displaying each applet provides explanation and instructions on how to use the applet. Below are brief descriptions of each applet with a link. Click on the "Home" link or use your browser's Back button to return to this page.

#### Correlation and Regression Applet

• CorrelationPicture--change the degree of organization in a scatterplot and observe the corresponding change in the correlation coefficient or, optionally, the least-squares regression line.
• CorrelationPoints--click on the graph to add data points; the correlation coefficient and, optionally, the least-squares regression line update.
• RegFit--dragging the slope of the regression line changes of the sum of squared errors and allows finding the least-squares regression line graphically.
• TaylorRussell--An interactive version of the Taylor-Russell diagram illustrates the effect of making selection decisions with an imperfect predictor variable.

#### Binomial Distribution

• BinomCalc--displays binomial probabilities for individual counts or for ranges of counts.

#### Normal Distribution

NormalShapes--illusrates the effects of changing the parameters of the mean and the standard deviation for the normal distribution.
• NormalProb--a graphical interface for calculating probabilities for the normal distribution.
• NormalHandle--a more interactive applet for computing normal probabilities.
• DensityCDF--illustrates the relationship between probability density and distribution functions using the normal distribution as an example.
• CohenD--illustrates the meaning of the effect size measure Cohen's d in terms of overlap between two normal distributions.

#### Correcting Conceptual Misunderstandings

Applets are very useful for helping correct common data analysis misunderstandings. Below are two examples.

• MedianSplit--illustrates the expected deleterious effects of dichotomizing a continuous variable at its median.
• ModeratorExplain--illustrates the meaning of the various parameters in a moderated regression model and allows user to observe changes in those parameters with different scalings of the predictor variable.
• QuadraticExplain--illustrates the meaning fo the various parameters in a quadratic model and allows user to observe changes in those parameters with different scalings of the predictor variable.