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1.4 KiB
title | slug | sidebar_position |
---|---|---|
varSamp | /en/sql-reference/aggregate-functions/reference/varSamp | 212 |
varSamp
Calculate the sample variance of a data set.
Syntax
varSamp(x)
Alias: VAR_SAMP
.
Parameters
Returned value
- Returns the sample variance of the input data set
x
. Float64.
Implementation details
The varSamp
function calculates the sample variance using the following formula:
\sum\frac{(x - \text{mean}(x))^2}{(n - 1)}
Where:
x
is each individual data point in the data set.mean(x)
is the arithmetic mean of the data set.n
is the number of data points in the data set.
The function assumes that the input data set represents a sample from a larger population. If you want to calculate the variance of the entire population (when you have the complete data set), you should use varPop
instead.
Example
Query:
DROP TABLE IF EXISTS test_data;
CREATE TABLE test_data
(
x Float64
)
ENGINE = Memory;
INSERT INTO test_data VALUES (10.5), (12.3), (9.8), (11.2), (10.7);
SELECT round(varSamp(x),3) AS var_samp FROM test_data;
Response:
┌─var_samp─┐
│ 0.865 │
└──────────┘