Excel Intercept Function

Intercept Equation

The Excel Intercept Function uses the following equation to calculate the intercept of the linear regression line through a set of given points:

Equation for the intercept of a linear regression line

where the slope, b is given by the equation:

Equation for the slope of a linear regression line

and the values of   x   and   y   are the sample means (the averages) of the known x- and y-values.

Related Function:
SLOPE

Function Description

The Excel Intercept function calculates the intercept (the value at the intersection of the y axis) of the linear regression line through a supplied set of x- and y- values.

The syntax of the function is:

INTERCEPT( known_y's, known_x's )

Where the arguments are:

known_y's-The array known y-values.
known_x's-

The array of known x-values.

Note that the length of the known_x's array should be the same length as known_y's, and the variance of the known_x's must not be zero.


Intercept Function Example

The spreadsheet below shows an example of the Excel Intercept function used to calculate the point at which the linear regression line through the known_x's and known_y's (listed in cells F2:F7 and G2:G7) intersects the y-axis.

The known_x's and known_y's are plotted on the chart in the spreadsheet.

Example of use of the Excel Intercept Function

As shown in cell F9 of the spreadsheet, the formula for the Intercept function is:

=INTERCEPT( G2:G7, F2:F7 )

which gives the result 2.4.

For further examples of the Excel Intercept function, see the Microsoft Office website


Intercept Function Errors

If you get an error from the Excel Intercept function, this is likely to be one of the following:

Common Errors
#N/A-Occurs if the supplied known_x's and known_y's arrays are of different lengths.
#DIV/0!-

Occurs if either:

  • The variance of the supplied known_x's is equal to zero
or
  • Either of the supplied known_x's or known_y's arrays is empty.