Microsoft Office Tutorials and References

In Depth Information

**What’s in the Future: Using FORECAST, TREND, and GROWTH to Make Predictions**

GROWTH

The GROWTH function is like TREND in that it uses existing data to predict Y

values for a set of X values. It’s different in that it’s designed for use with data

that fits an exponential model. The function takes four arguments:

✓
The first argument is a range or array containing the known Y values.

✓
The second argument is a range or array containing the known X values.

✓
The third argument is a range or array containing the X values for which

you want to calculate predicted Y values.

✓
The fourth value is omitted or TRUE if you want the constant
b

calculated normally. If this argument is FALSE,
b is forced to 1. You won’t use

FALSE except in special situations.

The number of known X and known Y values must be the same for the

GROWTH function or an error occurs. As you’d expect, GROWTH is an array

formula and must be entered accordingly.

To use the GROWTH function, follow these steps.
Note:
This assumes that

you have a worksheet that already contains known X and Y values that fit the

exponential model.

1. Enter the X values for which you want to predict Y values in a column

of the worksheet.

2. Select a range of cells in a column that has the same number of rows

as the X values you entered in Step 1.

Often this range is in the column next to the X values, but it doesn’t

have to be.

3. Enter
=Growth(
to start the function entry.

4. Drag the mouse over the range containing the known Y values, or

enter the range address.

5. Enter a comma (
,).

6. Drag the mouse over the range containing the known X values, or

enter the range address.

7. Enter a comma (
,).

8. Drag the mouse over the range containing the X values for which you

want to predict Y values, or enter the range address.

9. Enter a
).

10. Press Ctrl + Shift + Enter to complete the formula.