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:

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 Pagila database website.

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:

SELECT
    REGR_INTERCEPT(rating, length) AS YIntercept
FROM film;

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

     yintercept     
--------------------
 2.1055200882495355
(1 row)