> ## Documentation Index
> Fetch the complete documentation index at: https://docs.oxla.com/llms.txt
> Use this file to discover all available pages before exploring further.

# REGR_SLOPE()

## Overview

The `REGR_SLOPE()` aggregate function calculates the slope of the regression line for a linear relationship between a dependent variable (y) and an independent variable (x). The slope represents the rate of change in `y` for every unit increase in `x`. This function is used in regression analysis to quantify the strength and direction of a linear relationship.

## Syntax

The syntax for this function is as follows:

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

## Parameters

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

## Example

For the needs of this section, 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 query below uses the `REGR_SLOPE()` function to calculate the slope of the regression line for valid pairs of `rating` and `length`:

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

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

```sql theme={null}
        slope         
----------------------
 0.025985694391063227
(1 row)
```