Microsoft Office Tutorials and References

In Depth Information

**Using FORECAST to Calculate Prediction for Any One Data Point**

The FORECAST function calculates, or predicts, a future value by using

existing values. The predicted value is a y value for a given x value. The

known values are existing x values and y values, and the new value is pre-

dicted by using linear regression. You can use this function to predict future

sales, inventory requirements, or consumer trends.

The FORECAST function takes the following arguments:

•
x
—
This is the data point for which you want to predict a value. If x

is nonnumeric, FORECAST returns a #VALUE! error.

•
known_y's

known_y's
—
This is the dependent array or range of data.

•
known_x's

known_x's
—
This is the independent array or range of data.

If known_y'sand known_x'sare empty or contain a different number of data

points, FORECAST returns an #N/A error. If the variance of known_x's

equals 0, then FORECAST returns a #DIV/0! error.

Figure 14.17
shows actual sales data for the past decade. Years are in

column A, and sales are in column C. The sales data in C2:C12 is the range of

known_y's. The years in A2:A12 comprise the range of known_x's.