VAR_SAMP

Computes the sample variance of all non-NULL numeric values produced by an expression. The sample variance measures the average of the squared differences from the sample mean, indicating how spread out the values are within a sample. For information about the population variance, which measures how spread out the values are within the full population, see VAR_POP. Alias: VARIANCE

Syntax

{ VARIANCE | VAR_SAMP }(<expression>) [FILTER ([WHERE] <condition>)]

Parameters

Parameter	Description	Supported input types
`<expression>`	An expression producing numeric values for which to calculate the sample variance.	`REAL`, `DOUBLE PRECISION`
`<condition>`	An optional boolean expression to filter rows used in aggregation	`BOOL`

Return Type

VAR_SAMP returns a result of type DOUBLE PRECISION.

Special cases

If there is at most one non-NULL input value, the result is NULL.
If the input contains an Inf or NaN value, the result will be NaN.

Example

The following example calculates the sample variance of five grade values:

SELECT ROUND(VAR_SAMP(grade::double precision), 3) AS variance
FROM UNNEST(ARRAY[4.0, 3.7, 3.3, 2.7, 2.7]) AS t(grade);

variance double null
0.342

Rows: 1Execution time: 5.95ms

VAR_POP

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Example

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Syntax

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Example