Resource Library

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.

This collection is organized as discussions and activities in the subjects of descriptive statistics, inferential statistics, graphical analysis, and TI-83 and Excel guides. It also includes a section of quizzes. Key Words: Mean; Median; Mode; Normal Distribution; Skewed Distribution; Range; Standard Deviation; Confidence Interval; T-Test; ANOVA; Correlation; Regression; Chi-Square; Probability Distributions; Histograms; Scatterplots; Boxplot.

This module contains discussions on t-test, ANOVA, correlation, two-way factorial ANOVA, regression, chi-squared, and distributions and provides links to a variety of activities relevant to the discussions.

This tutorial on Distributions helps students understand the basic concept of probability distributions, recognize and use Binomial, Normal, Poisson, and Uniform Distributions, and solve exercise problems using probability distributions.

This interactive tutorial on Expectations helps students understand the concept of expectations, recognize and use variance and standard deviation, understand the method of moments, recognize and use co-variance, and solve exercise problems using expectations.

This case study addresses the question: "Will a smiling person accused of a crime be treated more leniently than one who is not smiling? If so, does the type of smile make a difference?" It concerns the following concepts: quantile/boxplots, contrasts among means, Dunnett's test, and Bonferroni correction.