*Choose Index below for a list of all words and phrases defined in this glossary.*

**Normal Distribution (Statistical)** - The charting of a data set in which most of the data points are concentrated around the average (mean), thus forming a bell shaped curve.

[Category=Quality ]

*Source: American Society for Quality, 09 October 2010 16:45:18, http://www.asq.org/glossary/ *

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**Normal Distribution** - Normal distribution is the spread of information (such as product performance or demographics) where the most frequently occurring value is in the middle of the range and other probabilities tail off symmetrically in both directions. Normal distribution is graphically categorized by a bell-shaped curve, also known as a Gaussian distribution. For normally distributed data, the mean and median are very close and may be identical.

[Category=Data Quality ]

*Source: iSixSigma, 07 February 2011 07:43:52, https: web.archive.org/web/20111109014246/http:www.isixsigma.com/index.php?option=com_glossary *

**normal distribution** - [statistics] A theoretical frequency distribution of a dataset in which the distribution of values can be graphically represented as a symmetrical bell curve. Normal distributions are typically characterized by a clustering of values near the mean, with few values departing radically from the mean. There are as many values on the left side of the curve as on the right, so the mean and median values for the distribution are the same. Sixty-eight percent of the values are plus or minus one standard deviation from the mean; 95 percent of the values are plus or minus two standard deviations; and 99 percent of the values are plus or minus three standard deviations.

[Category=Geospatial ]

*Source: esri, 20 June 2012 09:43:12, http://support.esri.com/en/knowledgebase/GISDictionary/term/abbreviation *

Data Quality Glossary. A free resource from GRC Data Intelligence. For comments, questions or feedback: dqglossary@grcdi.nl