Resource Library

In this activity, students will perform a chi-squared test on the number of people with health insurance by age to determine whether there is a relationship between age and insurance coverage. Questions about the exercise and a link to the DIG Stats Online Chi-Squared Calculator are given. The data exist in Excel and text formats.

In this activity, students will perform a one sample t-test to see if the pH level of rain collected by the EPA is less than the pH standard for acid rain (5.6). Questions about the exercise and links to a t-test applet and TI-83 instructions are given. The data exist in Excel, TI-83, and text formats.

In this activity, students will perform a two-way ANOVA on a dataset containing rainfall amounts for seeded and unseeded clouds in each of the 4 seasons. Questions about the exercise are given as well as a link to Excel instructions. The data exist in Excel and text formats.

In this activity, students will calculate the correlation and generate a scatterplot of the number of passengers flying and the number of performed departures from 135 airports in the US. Questions about the exercise and links to Excel and TI-83 instructions are given. The data exist in Excel, TI-83, and text formats.

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/

This free online video program "shows how to improve the accuracy of a survey by using stratified random sampling and how to avoid sampling errors such as bias. While surveys are becoming increasingly important tools in shaping public policy, a 1936 Gallup poll provides a striking illustration of the perils of undercoverage."

In this free online video program, "students will learn the distinction between deterministic phenomena and random sampling. This program introduces the concepts of sample space, events, and outcomes, and demonstrates how to use them to create a probability model. A discussion of statistician Persi Diaconis's work with probability theory covers many of the central ideas about randomness and probability."

This free online video program, "demonstrates how to determine the probability of any number of independent events, incorporating many of the same concepts used in previous programs. An interview with a statistician who helped to investigate the space shuttle accident shows how probability can be used to estimate the reliability of equipment."

This free online video program "lays out the parts of the confidence interval and gives an example of how it is used to measure the accuracy of long-term mean blood pressure. An example from politics and population surveys shows how margin of error and confidence levels are interpreted. The program also explains the use of a formula to convert the z* values into values on the sampling distribution curve. Finally, the concepts are applied to an issue of animal ethics."

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.