WorksheetFunction.Forecast Method
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.
Namespace: Microsoft.Office.Interop.Excel
Assembly: Microsoft.Office.Interop.Excel (in Microsoft.Office.Interop.Excel.dll)
Syntax
'Declaration
Function Forecast ( _
Arg1 As Double, _
Arg2 As Object, _
Arg3 As Object _
) As Double
'Usage
Dim instance As WorksheetFunction
Dim Arg1 As Double
Dim Arg2 As Object
Dim Arg3 As Object
Dim returnValue As Double
returnValue = instance.Forecast(Arg1, _
Arg2, Arg3)
double Forecast(
double Arg1,
Object Arg2,
Object Arg3
)
Parameters
Arg1
Type: System.DoubleX - the data point for which you want to predict a value.
Arg2
Type: System.ObjectKnown_y's - the dependent array or range of data.
Arg3
Type: System.ObjectKnown_x's - the independent array or range of data.
Return Value
Type: System.Double
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:
Figure 1: Equation for the Forecast method
.jpg "Equation for the Forecast method")
And:
Figure 2: Equation for the Forecast method
.jpg "Equation for the Forecast method")
and where x and y are the sample means AVERAGE(known_x's) and AVERAGE(known y's).