# Univariate Distributions

• ### Mean and Median

This applet allows students to manipulate a histogram and observe changes in the mean and median. The site includes links to exercises and descriptions of measures of center and spread.
• ### Markov Chain

This entry in the online encyclopeida, Wikipedia, describes Markov Chains, their properties, discrete state spaces, and formulas for calculating probabilities using Markov Chains. Links to examples and scientific applications are also included.
• ### Probability Sampling

This site describes in detail 5 different types of random sampling, giving examples, definitions, and procedures.
• ### Design Case Study: Planning a Study

This worksheet gives students 4 excercises in designing a case study. Each exercise presents a difference scenario and asks a series of questions about study design.
• ### Types of Surveys

This site discusses survey questionnaires and interviews, provides links to detailed descriptions and pros and cons of each, and describes how to conduct them.
• ### Survey Design

This site takes the user through the steps and decisions necessary when designing a survey. Pros and cons for each method are outlined and other issues in survey design are presented.
• ### Design of Experiments & ANOVA

This site lists definitions of key terms related to experimental design and ANOVA, including factorial, blocking, interaction, and others. This site is part of the "Statistics Glossary" for the STEPS project (STatistical Education through Problem Solving).
• ### Factorial Design

This site explains the 2x2 factorial experimental design, it's components, and it's effects. Graphs illustrate the concepts discussed.
• ### Confidence Intervals for Means Applet

This applet simulates finding confidence intervals for the mean of a normal random variable. A sample of size 20 is generated from a standard normal random variable. The blue marks represent the sample data. The sample mean X and sample standard deviation s are found and used to calculate the confidence interval. The black intervals are the confidence intervals which include the true mean 0, and the red intervals are those which exclude 0. This applet needs to be resized for optimal viewing.
• ### Normal Tool

This applet demonstrates probability as the area under the normal and the standard normal curves. Students can manipulate mean, standard deviation, and lower and upper bounds to find probabilities.