IStatistics.Trend

Trend(KnownYs: Array; KnownXs: Array; NewXs: Array; HasConstant: Boolean): Array;

Parameters

KnownYs. The range of Y values that are already known in ratio y=mx+b. Values contained in data array must be greater than zero. If there is only one column in the KnownYs array, each column of the KnownXs array is regarded as a separate variable. If there is only one row in the KnownYs array, each row of the KnownXs array is regarded as a separate variable. The KnownXs array can contain one or more variable sets. If only one variable is used, KnownYs and KnownXs can have any form, provided that they have the same dimension. If several variables are used, KnownYs must be a vector (i.e. an interval with a row height or a column width).

NewXs. New X values for which the Trend method returns corresponding Y values. Like KnownXs, NewXs must have a column or a row for each independent variable. Thus, if KnownYs has a single column, KnownXs and NewXs should have the same number of columns. If KnownYs is represented by one row, KnownXs and NewXs must have the same number of rows.

HasConstant. Boolean value that indicates whether the constant b must be equal to zero:

Description

The Trend method returns values for a linear trend. It approximates the KnownYs array and the KnownXs array using a straight line (the least-squares method). It returns Y values based on this straight line for the specified NewXs array.

Example

Sub UserProc;
Var
    st: Statistics;
    d0: Double;
    x, y, nx: Array Of Double;
    res: Array Of Double;
    i: Integer;
Begin
    y := New Double[12];
    x := New Double[12];
    nx := New Double[4];
    x[00] := 1; y[00] := 33100;
    x[01] := 2; y[01] := 47300;
    x[02] := 3; y[02] := 69000;
    x[03] := 4; y[03] := 102000;
    x[04] := 5; y[04] := 150000;
    x[05] := 6; y[05] := 220000;
    x[06] := 7; y[06] := 220100;
    x[07] := 8; y[07] := 247300;
    x[08] := 9; y[08] := 269000;
    x[09] := 10; y[09] := 270020;
    x[10] := 11; y[10] := 275210;
    x[11] := 12; y[11] := 276030;
    nx[0] := 13;
    nx[1] := 14;
    nx[2] := 15;
    nx[3] := 16;
    st := New Statistics.Create;
    res := st.Trend(y,x,x,True);
    Debug.WriteLine("Calculated values corresponding to existing values Y");
    For i := 0 To res.Length - 1 Do
        d0 := res[i];
        Debug.WriteLine(d0.ToString);
    End For;
    res := st.Trend(y,x,nx,True);
    Debug.WriteLine("Forecasted values Y for new values X (nx)" );
    For i := 0 To 3 Do
        d0 := res[i];
        Debug.WriteLine(d0.ToString);
    End For;
End Sub UserProc;

IStatistics.Trend

Syntax

Parameters

Description

Example