Glossary of statistical terms
Variance is a measure of dispersion. It is the average squared distance between the mean and each item in the population or in the sample.
An advantage of variance (as compared to the related measure of dispersion - the standard deviation) is that the variance of a sum of independent random variables is equal to the sum of their variances.
Note: When using the sample variance to estimate the population variance, the divisor (n-1) is typically used instead of (n) to calculate the average. The latter results in a biased estimate; the former is unbiased.
Want to learn more about this topic?
Statistics.com offers over 100 courses in statistics from introductory to advanced level. Most are 4 weeks long and take place online in series of weekly lessons and assignments, requiring about 15 hours/week. Participate at your convenience; there are no set times when you must to be online. Ask questions and exchange comments with the instructor and other students on a private discussion board throughout the course.
This course provides an easy introduction to statistics and statistical terminology through a series of practical applications. Once you've completed this course you'll be able to summarize data and interpret reports and newspaper accounts that use statistics and probability. You'll use simulation and resampling to fully grasp the difficult concept of "statistical significance."
This course, the first of a 3-course sequence, provides an introduction to statistics for those with little or no prior exposure to basic probability and statistics. It runs every eight weeks.
This course cover statistical probability distributions. Participants will learn how to identify which distribution(s) reasonably fit given data, and to evaluate the fit.
This course provides a solid introduction to the ideas and techniques of statistical modeling.