Statistics and Probability
This website provides training and tools to help you solve
statistics problems quickly, easily, and accurately - without
having to ask anyone for help.

Online Tutorials
Learn at your own pace. Free online tutorials cover
statistics, regression, probability samples, and matrix algebra - all explained in plain English.

Practice and review questions follow each lesson. Perfect for self-study.

AP Statistics
Here is your blueprint for test success on the AP Statistics exam.

AP Tutorial : Study our free, AP statistics tutorial to improve
your skills in all test areas.
Practice exam : Test your understanding of key topics,
through sample problems with detailed solutions.
Study guide : Read our review of the most popular AP study guides,
and choose the right guide for you.
Calculator :
Compare AP-approved graphing calculators, based on price and user
ratings.
A quick overview : Why you should take AP statistics, what is required to pass,
and how Stat Trek can help.
Be prepared. Get the score that you want on the AP Statistics test.

Random Number Generator
Produce a list of random numbers, based on your specifications.

Control list size (generate up to 1000 numbers).
Specify the range of values that appear in your list.
Permit or prevent duplicate entries.
Free and easy to use.

Random number generator
Sample Size Calculator
Create powerful, cost-effective survey sampling plans.

Find the optimum design (most precision,
least cost).
See how sample size affects cost and precision.
Compare different survey sampling methods.
Assess statistical power and Type II errors.
Tailor your sampling plan to your research needs.

Sample Size Calculator
Stat Toolbox
Check out our statistical tables and online calculators - fast, accurate, and user-friendly.

Each calculator features clear instructions plus answers to frequently-asked questions.

Acknowledgments
We wish to express our appreciation to those who assisted in the development of
this website. We are particularly grateful to the following folks.

Many thanks to Peter J. Acklam , who wrote the algorithm for
the Normal distribution, which you can view through the Wayback Machine at:
Acklam algorithm .
We are also grateful to Geoffrey C. Barnes , Ph.D, who wrote a
helpful VB.Net implementation of the Acklam algorithm, which is available through the Wayback Machine at:
Barnes VB implementation .
A big tip of the hat to Justus Randolph for discovering
and helping to correct an annoying bug in the Stat Trek
code.
We are indebted to Ian Smith for alerting us to
a problem with the chi square calculator and for his practical
suggestions to fix the problem.
We are grateful to Chris Headlee ,
a math teacher at Marion Senior High School in Virginia,
for thoughtful feedback that greatly improved our discussion
of the negative binomial.
And finally, thanks to James Ulatowski
of Mercedes, Texas for providing invaluable technical review which
uncovered many mistakes and omissions.
Note: AP and Advanced Placement Program are registered trademarks of the College Board,
which was not involved in the production of, and does not endorse this website.