measures of variation
The range of a sample is the difference between the largest and smallest value. The interquartile range is potentially more useful. If the sample is ranked in ascending order of magnitude two values of x may be found, the first of which is exceeded by 75% of the sample, the second by 25%; their difference is the interquartile range. An analogous definition applies to a probability distribution.
The variance is the expectation (or mean) of the square of the difference between a random variable and its mean; it is of fundamental importance in statistical analysis. The variance of a continuous distribution with mean μ is
and is denoted by σ2. The variance of a discrete distribution is
and is also denoted by σ2. The sample variance of a sample of n observations with mean x̄ is
and is denoted by s2. The value (n – 1) corrects for bias.
The standard deviation is the square root of the variance, denoted by σ (for a distribution) or s (for a sample). The standard deviation has the same units of measurement as the mean, and for a normal distribution about 5% of the distribution lies beyond about two standard deviations each side of the mean. The standard deviation of the distribution of an estimated quantity is termed the standard error.
The mean deviation is the mean of the absolute deviations of the random variable from the mean.
"measures of variation." A Dictionary of Computing. . Encyclopedia.com. (October 12, 2018). http://www.encyclopedia.com/computing/dictionaries-thesauruses-pictures-and-press-releases/measures-variation
"measures of variation." A Dictionary of Computing. . Retrieved October 12, 2018 from Encyclopedia.com: http://www.encyclopedia.com/computing/dictionaries-thesauruses-pictures-and-press-releases/measures-variation
Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).
Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.
Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:
Modern Language Association
The Chicago Manual of Style
American Psychological Association
- Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.
- In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.