lazarus-ccr/applications/lazstats/source/forms/analysis/nonparametric/signtestunit.pas

unit SignTestUnit;

{$mode objfpc}{$H+}

interface

uses
  Classes, SysUtils, Forms, Controls, Graphics, Dialogs, StdCtrls, Buttons, ExtCtrls,
  MainUnit, FunctionsLib, Globals, BasicStatsReportFormUnit;

type

  { TSignTestFrm }

  TSignTestFrm = class(TBasicStatsReportForm)
    Var1In: TBitBtn;
    Var1Out: TBitBtn;
    Var2In: TBitBtn;
    Var2Out: TBitBtn;
    Var1Edit: TEdit;
    Var2Edit: TEdit;
    Label1: TLabel;
    Label2: TLabel;
    Label3: TLabel;
    VarList: TListBox;
    procedure Var1InClick(Sender: TObject);
    procedure Var1OutClick(Sender: TObject);
    procedure Var2InClick(Sender: TObject);
    procedure Var2OutClick(Sender: TObject);
    procedure VarListDblClick(Sender: TObject);
    procedure VarListSelectionChange(Sender: TObject; {%H-}User: boolean);
  private
	
  protected
    procedure AdjustConstraints; override;
    procedure Compute; override;
    procedure UpdateBtnStates; override;
    function Validate(out AMsg: String; out AControl: TWinControl): boolean; override;
		
  public
    procedure Reset; override;
  end; 

var
  SignTestFrm: TSignTestFrm;

implementation

{$R *.lfm}

uses
  Math,
  GridProcs;


{ TSignTestFrm }

procedure TSignTestFrm.AdjustConstraints;
begin
  inherited;

  ParamsPanel.Constraints.MinWidth := 4*CloseBtn.Width + 3*CloseBtn.BorderSpacing.Left;
  ParamsPanel.Constraints.MinHeight := Var2Out.Top + Var2Out.Height +
    ButtonBevel.Height + CloseBtn.Height + CloseBtn.Borderspacing.Top;
end;


procedure TSignTestFrm.Compute;
var
  ColNoSelected: IntDyneVec = nil;
  DifSigns: IntDyneVec = nil;
  i, col1, col2, X, N, A, b, Temp: integer;
  p, Q, Probability, z, NoDiff, CorrectedA, x1, x2: double;
  SumProb: double;
  lReport: TStrings;
begin
  SumProb := 0.0;
  SetLength(DifSigns, NoCases);

  // Get column numbers and labels of variables selected
  SetLength(ColNoSelected, 2);
  ColNoSelected[0] := GetVariableIndex(OS3MainFrm.DataGrid, Var1Edit.Text);
  ColNoSelected[1] := GetVariableIndex(OS3MainFrm.DataGrid, Var2Edit.Text);

  p := 0.5;
  Q := 0.5;

  // Get sign of difference between pairs '(-1 := - ; 0 := no difference; +1 := +
  A := 0;
  b := 0;
  NoDiff := 0.0;
  for i := 1 to NoCases do
  begin
    if (not GoodRecord(OS3MainFrm.DataGrid, i, ColNoSelected)) then continue;
    col1 := ColNoSelected[0];
    col2 := ColNoSelected[1];
    x1 := StrToFloat(Trim(OS3MainFrm.DataGrid.Cells[col1, i]));
    x2 := StrToFloat(Trim(OS3MainFrm.DataGrid.Cells[col2, i]));
    if (x1 > x2) then
    begin
      DifSigns[i-1] := 1;
      A := A + 1;
    end;
    if (x1 < x2) then
    begin
      DifSigns[i-1] := -1;
      b  := b + 1;
    end;
    if (x1 = x2) then
    begin
      DifSigns[i-1] := 0;
      NoDiff := NoDiff + 1.0;
    end;
  end;

  // Show results
  lReport := TStringList.Create;
  try
    lReport.Add('RESULTS FOR THE SIGN TEST');
    lReport.Add('');
    lReport.Add('Frequency of %d out of %d observed + sign differences.', [A, NoCases]);
    lReport.Add('Frequency of %d out of %d observed - sign differences.', [b, NoCases]);
    lReport.Add('Frequency of %.0f out of %d observed no differences.', [NoDiff, NoCases]);
    lReport.Add('');
    lReport.Add('The theoretical proportion expected for +''s or -''s is 0.5 ');
    lReport.Add('The test is for the probability of the +''s or -''s (which ever is fewer)');;
    lReport.Add('as small or smaller than that observed given the expected proportion.');
    lReport.Add('');

    // Swap A and B around if A > B
    if (A > b) then
    begin
      Temp := A;
      A := b;
      b := Temp;
    end;

    N := A + b;
    if (N > 25) then // Use normal distribution approximation
    begin
      CorrectedA := A;
      if (A < N * p) then  CorrectedA := A + 0.5;
      if (A > N * p) then CorrectedA := A - 0.5;
      z := (CorrectedA - N * p) / sqrt(N * p * Q);
      lReport.Add('Z value for Normal Distribution approximation: %.3f', [z]);
      Probability := ProbZ(z);
      lReport.Add('Probability: %.4f', [Probability]);
    end
    else // Use binomial fomula
    begin
      X := 0;
      while X <= A do
      begin
        Probability := combos(X, N) * Power(p,X) * Power(Q,(N - X));
        lReport.Add('Binary Probability of %3d: %6.4f', [X, Probability]);
        SumProb := SumProb +  Probability;
        X := X + 1;
      end;
      lReport.Add('Binomial Probability of %d or smaller out of %d: %.4f', [A, N, SumProb]);
    end;

    FReportFrame.DisplayReport(lReport);

  finally
    lReport.Free;
  end;
end;


procedure TSignTestFrm.Reset;
var
  i: integer;
begin
  inherited;
  Var1Edit.Clear;
  Var2Edit.Clear;
  VarList.Items.Clear;
  for i := 1 to NoVariables do
    VarList.Items.Add(OS3MainFrm.DataGrid.Cells[i,0]);
  UpdateBtnStates;
end;


function TSignTestFrm.Validate(out AMsg: String; out AControl: TWinControl): boolean;
begin
  Result := false;
	
  if Var1Edit.Text = '' then
  begin
    AMsg := 'Variable 1 not selected.';
    AControl := Var1Edit;
    exit;
  end;

  if Var2Edit.Text = '' then
  begin
    AMsg := 'Variable 2 not selected.';
    AControl := Var2Edit;
    exit;
  end;

  Result := true;
end;

	
procedure TSignTestFrm.Var1InClick(Sender: TObject);
var
  index: integer;
begin
  index := VarList.ItemIndex;
  if (index > -1) and (Var1Edit.Text = '') then
  begin
    Var1Edit.Text := VarList.Items[index];
    VarList.Items.Delete(index);
  end;
  UpdateBtnStates;
end;


procedure TSignTestFrm.Var1OutClick(Sender: TObject);
begin
  if Var1Edit.Text <> '' then
  begin
    VarList.Items.Add(Var1Edit.Text);
    Var1Edit.Text := '';
  end;
  UpdateBtnStates;
end;


procedure TSignTestFrm.Var2InClick(Sender: TObject);
var
  index: integer;
begin
  index := VarList.ItemIndex;
  if (index > -1) and (Var2Edit.Text = '') then
  begin
    Var2Edit.Text := VarList.Items[index];
    VarList.Items.Delete(index);
  end;
  UpdateBtnStates;
end;


procedure TSignTestFrm.Var2OutClick(Sender: TObject);
begin
  if Var2Edit.Text <> '' then
  begin
    VarList.Items.Add(Var2Edit.Text);
    Var2Edit.Text := '';
  end;
  UpdateBtnStates;
end;


procedure TSignTestFrm.VarListDblClick(Sender: TObject);
var
  index: Integer;
  s: String;
begin
  index := Varlist.ItemIndex;;
  if index > -1 then
  begin
    s := VarList.Items[index];
    if Var1Edit.Text = '' then
      Var1Edit.Text := s
    else
    if Var2Edit.Text = '' then
      Var2Edit.Text := s;
    Varlist.Items.Delete(index);
    UpdateBtnStates;
  end;
end;


procedure TSignTestFrm.VarListSelectionChange(Sender: TObject; User: boolean);
begin
  UpdateBtnStates;
end;


procedure TSignTestFrm.UpdateBtnStates;
begin
  Var1In.Enabled := (VarList.ItemIndex > -1) and (Var1Edit.Text = '');
  Var2In.Enabled := (VarList.ItemIndex > -1) and (Var2Edit.Text = '');
  Var1Out.Enabled := (Var1Edit.Text <> '');
  Var2Out.Enabled := (Var2Edit.Text <> '');
end;


end.