Observations of a less serious or isolated nature that are not deemed Critical or Major but require correction or suggestions given on how to improve systems or procedures that may be compliant but would benefit from improvement.
In statistics, the standard deviation is a measure of the amount of variation of the values of a variable about its (arithmetic) average. A low standard deviation indicates that the values of a set tend to be close to their average, while a high standard deviation indicates that the values are spread out over a wider range. Standard deviation may be abbreviated SD or std dev, and is most commonly represented in mathematical texts and equations by the lowercase Greek letter σ (sigma).
The standard deviation of a random variable, sample, statistical population, data set or probability distribution is the square root of its variance (the variance being the average of the squared deviations from the mean). A useful property of the standard deviation is that, unlike the variance, it is expressed in the same unit as the data. Standard deviation can also be used to calculate standard error for a finite sample, and to determine statistical significance.
When only a sample of data from a population is available, the term standard deviation of the sample or sample standard deviation can refer to either the above-mentioned quantity as applied to those data, or to a modified quantity that is an unbiased estimate of the population standard deviation (the standard deviation of the entire population).
English
Etymology
Coined by English mathematician, biometrician, and eugenicist Karl Pearson in 1894 in his paper "On the dissection of asymmetrical frequency curves".
Pronunciation
Noun
standard deviation (plural standard deviations)
- (statistics) A measure of how spread out data values are around the mean, defined as the square root of the variance. Represented with the Greek letter σ (sigma).
Synonyms
- standard error
- sigma
Translations
Further reading
- standard deviation on Wikipedia.