Microsoft Office Tutorials and References

In Depth Information

**Using GROWTH to Predict Many Data Points from an Exponential Regression**

Using

Using
GROWTH

GROWTH
to Predict Many Data Points from an Exponential Regression

to Predict Many Data Points from an Exponential Regression

As the TREND function is able to extrapolate points from a linear regres-

sion, the GROWTH function is able to extrapolate points from an exponential

regression.

Syntax

=GROWTH(known_y's,known_x's,new_x's,const)

The GROWTH function calculates predicted exponential growth by using ex-

isting data. GROWTH returns the y values for a series of new x values that

you specify by using existing x values and y values. You can also use the

GROWTH worksheet function to fit an exponential curve to existing x values

and y values. This function takes the following arguments:

•
known_y's

known_y's
—
This is the set of y values you already know in the re-

lationship y = b × m^x. If the array known_y'sis in a single column,

each column of known_x'sis interpreted as a separate variable. If

the array known_y'sis in a single row, each row of known_x'sis in-

terpreted as a separate variable. If any of the numbers in known_y's

is 0 or negative, GROWTH returns a #NUM! error.

•
known_x's

known_x's
—
This is an optional set of x values that you may

already know in the relationship y = b × m^x. The array known_x
’
s

can include one or more sets of variables. If only one variable is

used, known_y'sand known_x'scan be ranges of any shape, as long as

they have equal dimensions. If more than one variable is used,

known_y'smust be a vector (that is, a range with a height of one row

or a width of one column). If known_x'sis omitted, it is assumed to be

the array {1,2,3,...} that is the same size as known_y's.

Tip

When you have formulas that return arrays, you must enter them

as array formulas after selecting the correct number of cells. To

specify an array formula, you hold down Ctrl+Shift while pressing

Enter.

•
new_x's

new_x's
—
These are new x values for which you want GROWTH to re-

turn corresponding y values. new_x'smust include a column (or row)