This website lists five different types of probability sampling, giving the advantages and disadvantages of each.

This article addresses the reporting of meta-analyses of observational studies in order to aid authors, reviewers, editors and readers when reading or writing such reports.

This article gives a description of typical sources of error in public opinion polls. It gives a short but insightful explanation of what the margin of error indicates as well as other common errors in opinion polls.

Students can sample numerous bags of M&Ms. A plot of the relative frequency of each color is continually updated above the sampling frame. Each sample bag of M&Ms contains 56 candies.

This exercise will help the user understand the logic and procedures of hypothesis testing. To make best use of this exercise, the user should know how to use a z table to find probabilities on a normal distribution, and how to calculate the standard error of a mean. Relevant review materials are available from the links provided. The user will need a copy of the hypothesis testing exercise (link is provided), a table for the standardized normal distribution (z), and a calculator. The user will be asked several questions and will be given feedback regarding their answers. Detailed solutions are provided, but users should try to answer the questions on their own before consulting the detailed solutions. The end of the tutorial contains some "thought" questions.

A small collection of applets on the following topics: Introduction to Probability Models, Hypergeometric Distribution, Poisson Distribution, Normal Distribution, Proportions, Confidence Intervals for Means, The Central Limit Theorem, Bivariate Normal Distribution, Linear Regression, Buffon's Needle Problem.

Gives an overview of variables, classifications, measurements, relations, and other basic statistical concepts. Also contains two animated graphs.

This site discusses the issues of reliability and vailidity as related to research.

This tutorial introduces 9 sources of threat to internal vailidity and asks the user to classify hypothetical experiments as either internally valid or invalid and identify the source of threat if invalid.

The applet in this section allows for simple data analysis of univariate data. Users can either generate normal or uniform data for k samples or copy and paste data from another source to a text box. A univariate analysis is performed for all k samples. A two-sample t-test (Pooled and Satterthwaite) is performed for k = 2. An ANOVA test is performed for k > 2. This page was formerly located at http://www.stat.vt.edu/~sundar/java/applets/Data.html