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albertmeronyo/sd.sparql

Created April 29, 2015 14:32
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Standard deviation in (pure) SPARQL
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sd.sparql
SELECT ((SUM((?n - ?mean)*(?n - ?mean)))/(COUNT(?n) - 1) AS ?sdev) WHERE {
?obs qb:value ?n .
{
SELECT (AVG(?n) AS ?mean) WHERE {
?obs qb:value ?n .
}
}
@bas-stringer
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This actually calculates variance, (including Bessel's correction). To go from this to a standard deviation requires a square root operation, which isn't available in pure SPARQL.

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