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FORECAST

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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 predicted by using linear regression. You can use this function to predict future sales, inventory requirements, or consumer trends.

Syntax

FORECAST(x,known_y's,known_x's)

X    is the data point for which you want to predict a value.

Known_y's    is the dependent array or range of data.

Known_x's    is the independent array or range of data.

Remarks

• If x is nonnumeric, FORECAST returns the #VALUE! error value.
• If known_y's and known_x's are empty or contain a different number of data points, FORECAST returns the #N/A error value.
• If the variance of known_x's equals zero, then FORECAST returns the #DIV/0! error value.
• The equation for FORECAST is a+bx, where:

  

  and:

  

  and where x and y are the sample means AVERAGE(known_x's) and AVERAGE(known y's).

Example

The example may be easier to understand if you copy it to a blank worksheet.

How?