# Source: https://docs.oxla.com/sql-reference/sql-functions/aggregate-functions/regr-intercept.md

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# REGR_INTERCEPT()

## Overview

The `REGR_INTERCEPT()` aggregate function calculates the y-intercept of the univariate linear regression line for a group of data points, where the dependent variable is (y) and the independent variable is (x). The intercept is the point where the regression line crosses the y-axis when x=0.

## Syntax

The syntax for this function is as follows:

```sql  theme={null}
REGR_INTERCEPT(y, x)
```

## Parameters

* `y`: variable being predicted
* `x`: variable used for prediction

## Example

We're going to use a simplified version of the `film` table from the Pagila database, containing only the `title`, `length` and `rating` columns. The complete schema for the `film` table can be found on the
<a href="https://www.postgresql.org/ftp/projects/pgFoundry/dbsamples/pagila/pagila/" target="_blank">Pagila</a> database website.

```sql  theme={null}
DROP TABLE IF EXISTS film;
CREATE TABLE film (
  title text NOT NULL,
  length int,
  rating int
);
INSERT INTO film(title, length, rating) VALUES
  ('ATTRACTION NEWTON', 83, 5),
  ('CHRISTMAS MOONSHINE', 150, 7),
  ('DANGEROUS UPTOWN', 121, 4),
  ('KILL BROTHERHOOD', 54, 3),
  ('HALLOWEEN NUTS', 47, 5),
  ('HOURS RAGE', 122, 7),
  ('PIANIST OUTFIELD', 136, 7),
  ('PICKUP DRIVING', 77, 3),
  ('INDEPENDENCE HOTEL', 157, 7),
  ('PRIVATE DROP', 106, 4),
  ('SAINTS BRIDE', 125, 3),
  ('FOREVER CANDIDATE', 131, 7),
  ('MILLION ACE', 142, 5),
  ('SLEEPY JAPANESE', 137, 4),
  ('WRATH MILE', 176, 7),
  ('YOUTH KICK', 179, 7),
  ('CLOCKWORK PARADISE', 143, 5);
```

The above query uses the `REGR_INTERCEPT()` function to calculate the y-intercept of the regression line for valid pairs of `rating` and `length`:

```sql  theme={null}
SELECT
    REGR_INTERCEPT(rating, length) AS YIntercept
FROM film;
```

By running the code above we will get the following output:

```sql  theme={null}
     yintercept     
--------------------
 2.1055200882495355
(1 row)
```