In this video, Salman Khan of Khan Academy explains alternate variance formulas.
Khan Academy

Discusses Bayes' theorem in relation to mutually exclusive events and 2 ways to calculate the statement.
Interactive Mathematics

In this Early Edge video lesson, you'll learn more about Mean, so you can be successful when you take on highschool Math & Arithmetic.
The Princeton Review

Flash tutorial with clear explanations about what deviation and variance mean along with how to calculate these by hand, using Excel and using the calculator.
Usable Stats

Very comprehensive list of statistics formulas.
Stat Trek

It also gives formulas, description, etc for statistics.
Wolfram Mathworld

In this Early Edge video lesson, you'll learn more about Mode, so you can be successful when you take on highschool Math & Arithmetic.
The Princeton Review

In this Early Edge video lesson, you'll learn more about Median, so you can be successful when you take on highschool Math & Arithmetic.
The Princeton Review

Site gives detailed explanation of what a confidence interval implies and how to construct one.
Stat Trek

Site gives formulas and examples for testing a null hypothesis and analyzing the result.
Lake Tahoe Community College  Professor Green's Home Page
