> ## Documentation Index
> Fetch the complete documentation index at: https://mintlify-poc.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# corr()

> Calculate the correlation coefficient from a two-dimensional statistical aggregate

<Icon icon="tag" iconType="duotone" /> Since [1.3.0][toolkit-1.3.0]

Calculate the correlation coefficient from a two-dimensional statistical aggregate. The calculation uses the standard
least-squares fitting for linear regression.

## Samples

Calculate the correlation coefficient of independent variable `y` and dependent variable `x` for each 15-minute time
bucket:

```sql theme={"dark"}
SELECT
  id,
  time_bucket('15 min'::interval, ts) AS bucket,
  corr(stats_agg(y, x)) AS summary
FROM foo
GROUP BY id, time_bucket('15 min'::interval, ts)
```

## Arguments

The syntax is:

```sql theme={"dark"}
corr(
  summary StatsSummary2D
) RETURNS DOUBLE PRECISION
```

| Name    | Type           | Default | Required | Description                                              |
| ------- | -------------- | ------- | -------- | -------------------------------------------------------- |
| summary | StatsSummary2D | -       | ✔        | The statistical aggregate produced by a `stats_agg` call |

## Returns

| Column | Type             | Description                                               |
| ------ | ---------------- | --------------------------------------------------------- |
| corr   | DOUBLE PRECISION | The correlation coefficient of the least-squares fit line |

[toolkit-1.3.0]: https://github.com/timescale/timescaledb-toolkit/releases/tag/1.3.0