---
title: corr() | Tiger Data Docs
description: Calculate the correlation coefficient from a two-dimensional statistical aggregate
---

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

```
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:

```
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 |