# Multivariate Quantitative Relationships

• ### DIG Stats: TI-83 Guide for Calculating Correlation

This tutorial explains in detail how to calculate correlation with a TI-83 graphing calculator.
• ### DIG Stats: Excel Guide for Determining the Confidence Interval

This tutorial explains in detail how to find a confidence interval using Excel.
• ### DIG Stats: Excel Guide for Making a Scatterplot

This tutorial explains in detail how to make a scatterplot in Excel.
• ### Exponential Probabilities

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
• ### Normal Distribution

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/
• ### T Probabilities

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
• ### Data+Applet : Regression by Eye

In this demonstration a scatterplot is displayed and you draw in a regression line by hand. You can then compare your line to the best least squares fit. You can also try to guess the value of Pearson's correlation coefficient.
• ### Dataset Example: Reliability and Regression Analysis

This applet demonstrates how the reliability of X and Y affect various aspects of the regression of Y on X.
• ### Regression to the Mean

This is a simulation illustrating the regression toward the mean phenomenon.
• ### Robustness of t test and ANOVA

This applet lets you explore the effect of violations of the assumptions of normality and homogeneity of variance on the type I error rate and power of t tests (and two-group analysis of variance).