In the function syntax, y is interpreted as an x-dependent variable.

The linear regression aggregate functions take a pair of arguments, the dependent variable expression (y) and the independent variable expression (x), which are both numeric value expressions. Any row in which either argument evaluates to NULL is removed from the rows that qualify. If there are no rows that qualify, then the result of REGR_COUNT is 0 (zero), and the other linear regression aggregate functions result in NULL.

Available inDSQL, PSQL

Result typeDOUBLE PRECISION

Syntax

Table 9.4.1.1 REGR_AVGX Function Parameters

The function REGR_AVGX calculates the average of the independent variable (x) of the regression line.

The function REGR_AVGX(<y>, <x>) is equivalent to

SUM(<exprX>) / REGR_COUNT(<y>, <x>)
 
<exprX> :==
  CASE WHEN <x> IS NOT NULL AND <y> IS NOT NULL THEN <x> END

See also, Section 9.4.3, REGR_COUNT(),

9.4.2 REGR_AVGY()

Available inDSQL, PSQL

Result typeDOUBLE PRECISION

Syntax

REGR_AVGY ( <y>, <x> )

Table 9.4.2.1 REGR_AVGY Function Parameters

The function REGR_AVGY calculates the average of the dependent variable (y) of the regression line.

The function REGR_AVGY(<y>, <x>) is equivalent to

SUM(<exprY>) / REGR_COUNT(<y>, <x>)
 
<exprY> :==
  CASE WHEN <x> IS NOT NULL AND <y> IS NOT NULL THEN <y> END

See also, Section 9.4.3, REGR_COUNT(),

9.4.3 REGR_COUNT()

Available inDSQL, PSQL

Result typeDOUBLE PRECISION

Syntax

REGR_COUNT ( <y>, <x> )

Table 9.4.3.1 REGR_COUNT Function Parameters

The function REGR_COUNT counts the number of non-empty pairs of the regression line.

SUM(<exprXY>) / REGR_COUNT(<y>, <x>)
 
<exprXY> :==
  CASE WHEN <x> IS NOT NULL AND <y> IS NOT NULL THEN 1 END

See also

Available inDSQL, PSQL

Result typeDOUBLE PRECISION

Syntax

Table 9.4.4.1 REGR_INTERCEPT Function Parameters

The function REGR_INTERCEPT calculates the point of intersection of the regression line with the y-axis.

The function REGR_INTERCEPT(<y>, <x>) is equivalent to

REGR_AVGY(<y>, <x>) - REGR_SLOPE(<y>, <x>) * REGR_AVGX(<y>, <x>)

9.4.4.1 REGR_INTERCEPT Examples

Forecasting sales volume

with recursive years (byyear) as (
  from rdb$database
  union all
  select byyear + 1
  from years
  where byyear < 2020
),
s as (
  select
    extract(year from order_date) as byyear,
    sum(total_value) as total_value
  from sales
  group by 1
),
regr as (
  select
    regr_intercept(total_value, byyear) as intercept,
    regr_slope(total_value, byyear) as slope
  from s
)
select
  years.byyear as byyear,
  intercept + (slope * years.byyear) as total_value
from years
cross join regr

BYYEAR TOTAL_VALUE
------ ------------
  1992    414557.62
  1993    710737.89
  1994   1006918.16
  1995   1303098.43
  1996   1599278.69
  1997   1895458.96
  1998   2191639.23
  2000   2783999.77
...

See also, Section 9.4.2, REGR_AVGY(),

9.4.5 REGR_R2()

Available inDSQL, PSQL

Result typeDOUBLE PRECISION

Syntax

REGR_R2 ( <y>, <x> )

Table 9.4.5.1 REGR_R2 Function Parameters

The REGR_R2 function calculates the coefficient of determination, or R-squared, of the regression line.

The function REGR_R2(<y>, <x>) is equivalent to

POWER(CORR(<y>, <x>), 2)

See also, POWER

9.4.6 REGR_SLOPE()

Available inDSQL, PSQL

Result typeDOUBLE PRECISION

Syntax

Table 9.4.6.1 REGR_SLOPE Function Parameters

The function REGR_SLOPE calculates the slope of the regression line.

COVAR_POP(<y>, <x>) / VAR_POP(<exprX>)
 
<exprX> :==
  CASE WHEN <x> IS NOT NULL AND <y> IS NOT NULL THEN <x> END

See alsoSection 9.3.2, COVAR_POP(),

Available inDSQL, PSQL

Result typeDOUBLE PRECISION

Syntax

REGR_SXX ( <y>, <x> )

Table 9.4.7.1 REGR_SXX Function Parameters

The function REGR_SXX calculates the sum of squares of the independent expression variable (x).

The function REGR_SXX(<y>, <x>) is equivalent to

REGR_COUNT(<y>, <x>) * VAR_POP(<exprX>)
 
<exprX> :==
  CASE WHEN <x> IS NOT NULL AND <y> IS NOT NULL THEN <x> END

See alsoSection 9.4.3, REGR_COUNT(),

9.4.8 REGR_SXY()

Available inDSQL, PSQL

Result typeDOUBLE PRECISION

Syntax

REGR_SXY ( <y>, <x> )

Table 9.4.8.1 REGR_SXY Function Parameters

The function REGR_SXY calculates the sum of products of independent variable expression (x) times dependent variable expression (y).

The function REGR_SXY(<y>, <x>) is equivalent to

REGR_COUNT(<y>, <x>) * COVAR_POP(<y>, <x>)

See also, Section 9.4.3, REGR_COUNT()

9.4.9 REGR_SYY()

Available inDSQL, PSQL

Result typeDOUBLE PRECISION

Syntax

Table 9.4.9.1 REGR_SYY Function Parameters

The function REGR_SYY calculates the sum of squares of the dependent variable (y).

The function REGR_SYY(<y>, <x>) is equivalent to

REGR_COUNT(<y>, <x>) * VAR_POP(<exprY>)
 
<exprY> :==