[Black Raider]

Вот так:

Код:

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs;

type
  TForm1 = class(TForm)
    procedure Regress(num: integer);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}
procedure Tform1.Regress(num: integer); {num кол-во элементов}
var
 a, b, x_avg, y_avg, temp, temp2, cor: real;
 t, min, max: integer;
 ch: char;
begin
 y_avg := 0;
 x_avg := 0;
 for t := 1 to num do
 begin
  y_avg := y_avg + StrToFloat(StringGrid1.Cells[t,1]);
  x_avg := x_avg + StrToFloat(StringGrid1.Cells[t,0]);
 end;
 x_avg := x_avg/num;
 y_avg := y_avg/num;
 
 temp := 0; temp2 := 0;
 for t := 1 to num do
 begin
  temp := temp +(StrToFloat(StringGrid1.Cells[t,1]) - y_avg)*(StrToFloat(StringGrid1.Cells[t,0])-x_avg);
  temp2 := temp2 +(t - x_avg)*(t-x_avg);
 end;
 
  b := temp/temp2;
  a := y_avg-(b*x_avg);
 
 Image1.Canvas.Brush.Color:=clWhite;
 Image1.Canvas.Pen.Color:=clWhite;
 Image1.Canvas.Rectangle(0,0,Image1.Width,Image1.Height);
 
 Image1.Canvas.Brush.Color:=clRed;
 Image1.Canvas.Pen.Color:=clRed;
 For t:=1 to num do
  image1.Canvas.Ellipse(Trunc(StrToFloat(StringGrid1.Cells[t,0]))-2,Image1.Height -Trunc(StrToFloat(StringGrid1.Cells[t,1]))-2,
                        Trunc(StrToFloat(StringGrid1.Cells[t,0]))+2,Image1.Height -Trunc(StrToFloat(StringGrid1.Cells[t,1]))+2);
 
 Image1.Canvas.Pen.Color:=clBlack;
 
 image1.Canvas.MoveTo(1, Image1.Height - Trunc(a+b));
 image1.Canvas.LineTo(100,Image1.Height - Trunc(a+b*100));
 
 Label2.Caption:='Y = '+FloatToStr(Trunc(b*100)/100)+'x + '+FloatToStr(Trunc(a*100)/100);
end;

end.

Компоненты сами на форму накидаете!
киньте кнопку и 2 раза на нее нажмите:
появится ее (кнопки) обработчик туда впишите
чтоб было так:

Код:

procedure TForm1.Button1Click(Sender: TObject);
begin
Regress(12);
end;