Apple iWork '09 - Manual (Page 287)

Chapter 10 Statistical Functions 287
SLOPE
The SLOPE function returns the slope of the best-fit line for the collection using linear
regression analysis.
SLOPE(y-values, x-values)
 y-values: The collection containing the y (dependent) values. y-values is a collection
that can contain number, date/time, or duration values. All values must be of the
same type.
 x-values: The collection containing the x (independent) values. x-values is a
collection that can contain number, date/time, or duration values. All values must be
of the same type.
Usage Notes
The two collections must be of the same size or the function returns an error. Â
If, for example, you had data on the driving speed of a vehicle and its fuel efficiency Â
at each speed, fuel efficiency would be the dependent variable and driving speed
would be the independent variable.
To find the y-intercept of the best-fit line, use the INTERCEPT function.
Â
Example
In this example, the SLOPE function is used to determine the slope of the best-fit line for the
temperature that this hypothetical homeowner has set on the thermostat (the dependent variable),
based on the price of heating oil (the independent variable).
=SLOPE(B2:B11, A2:A11) evaluates to approximately -3.2337, indicating a best-fit line sloping
downward (as prices rose, the thermostat was lowered).
Related Topics
For related functions and additional information, see:
“INTERCEPT” on page 262
“Listing of Statistical Functions” on page 225
“Value Types” on page 36