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/en/sql-reference/aggregate-functions/reference/cramersv | 351 |
cramersV
Cramer's V (sometimes referred to as Cramer's phi) is a measure of association between two columns in a table. The result of the cramersV
function ranges from 0 (corresponding to no association between the variables) to 1 and can reach 1 only when each value is completely determined by the other. It may be viewed as the association between two variables as a percentage of their maximum possible variation.
Syntax
cramersV(column1, column2)
Arguments
column1
andcolumn2
are the columns to be compared
Returned value
- a value between 0 (corresponding to no association between the columns' values) to 1 (complete association).
Return type is always Float64.
Example
The following two columns being compared below have no association with each other, so the result of cramersV
is 0:
SELECT
cramersV(a, b)
FROM
(
SELECT
number % 3 AS a,
number % 5 AS b
FROM
numbers(150)
);
Result:
┌─cramersV(a, b)─┐
│ 0 │
└────────────────┘
The following two columns below have a fairly close association, so the result of cramersV
is a high value:
SELECT
cramersV(a, b)
FROM
(
SELECT
number % 10 AS a,
number % 5 AS b
FROM
numbers(150)
);
Result:
┌─────cramersV(a, b)─┐
│ 0.8944271909999159 │
└────────────────────┘