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 — This is the dependent array or range of data.
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.