Resource Library

This website provides data files, examples, guides that are referenced in David Howell's textbook published in 2013. There is also a student manual and links to other useful websites.

This activity provides students with 24 histograms representing distributions with differing shapes and characteristics. By sorting the histograms into piles that seem to go together, and by describing those piles, students develop awareness of the different versions of particular shapes (e.g., different types of skewed distributions, or different types of normal distributions), that not all histograms are easy to classify, that there is a difference between models (normal, uniform) and characteristics (skewness, symmetry, etc.). Key words: Histogram, shape, normal, uniform, skewed, symmetric, bimodal

This page is a collection of examples, demonstrations, and exercises that can be used to motivate a lecture, demonstrate an important point, or create a laboratory exercise for students. Topics include the following: Descriptives, Normal Distribution, Sampling Distributions, Probability, Chi-Square, t tests, Power, Correlation/Regression, One-way Anova, Multiple Comparisons, Factorial Anova, Repeated Measures, Multiple Regression, General Linear Model, Log Linear Models, and Distribution-Free Tests.

This is an article published in the Journal of Statistics Education describing the ANOVA Visualization Tool and how it can be used in class.

This Java applet helps students visualize features and factors of one and two-way ANOVA tables together with representational models and model parameters.

The applet in this section allows you to see how the T distribution is related to the Standard Normal distribution by calculating probabilities. The T distribution is primarily used to make inferences on a Normal mean when the variance is unknown. If the variance is known inference on the mean can be done using the Standard Normal. The user has a choice of three different probability expressions, then can change the degrees of freedom and the limits of probability. This page was formerly located at http://www.stat.vt.edu/~sundar/java/applets/TNormal.html

The applets in this section allow users to see how probabilities and quantiles are determined from a Normal distribution. For calculating probabilities, set the mean, variance, and limits; for calculating quantiles, set the mean, variance, and probability. Users can choose from three different probability expressions. Variance is restricted to numbers between 0.1 and 10, inclusive. To select between the different applets you can click on Statistical Theory, Normal Distribution and then the Main Page. At the bottom of this page you can make your applet selection. This page was formerly located at http://www.stat.vt.edu/~sundar/java/applets/

The applet in this section allows you see how probabilities are determined from the exponential distribution. The user determines the mean of the distribution and the limits of probability. Three different probability expressions are available. Click "Calculate" to see the pdf and the cdf. The probability is highlighted in green on the pdf. This page was formerly located at http://www.stat.vt.edu/~sundar/java/applets/ExpDensity.html

In this activity, students will perform a t-test to see if fecal coliform counts collected from Blackwater Creek in Lynchburg, Virginia differ before and after rain showers. Questions about the exercise and links to Excel and TI-83 instructions are given. The data exist in Excel, TI-83, and text formats.

In this activity, students will calculate confidence intervals for the mean weight (in milligrams) of seed harvester ants for 4 size classes of the ants. Questions about the exercise and links to Excel and TI-83 instructions are given. This data exists in Excel, TI-83, and text formats.