LazStats: First refactoring of WLSUnit.

git-svn-id: https://svn.code.sf.net/p/lazarus-ccr/svn@7773 8e941d3f-bd1b-0410-a28a-d453659cc2b4

applications/lazstats/source/forms/analysis/descriptive/plotxyunit.pas

@@ -205,11 +205,7 @@ begin
     ser := FChartFrame.PlotXY(ptLines, XPoints, conf, nil, nil, 'Lower confidence band', clRed);
     rightLabels.Add(ser.yValue[ser.Count-1], ser.YValue[ser.Count-1], 'LCL');
   end;
-                {
+
-  FChartFrame.Chart.Prepare;
-  FChartFrame.GetXRange(xmin, xmax, false);
-  FChartFrame.GetYRange(ymin, ymax, false);
-                 }
   // Draw means
   if MeansChk.Checked then
     with ARegressionResults do

applications/lazstats/source/forms/analysis/multiple_regression/wlsunit.pas

@@ -7,14 +7,14 @@ interface
 uses
   Classes, SysUtils, FileUtil, Forms, Controls, Graphics, Dialogs,
   StdCtrls, Buttons, ExtCtrls, ComCtrls,
-  Globals, MainUnit, DictionaryUnit, Matrixlib,
+  Globals, MainUnit, DictionaryUnit, Matrixlib, DataProcs,
-  DataProcs, BlankFrmUnit, ReportFrameUnit, ChartFrameUnit, BasicStatsParamsFormUnit; //BasicStatsReportAndChartFormUnit;
+  MathUnit, ReportFrameUnit, ChartFrameUnit, BasicStatsParamsFormUnit;
 
 type
 
   { TWLSFrm }
 
-  TWLSFrm = class(TBasicStatsParamsForm)  //TBasicStatsReportAndChartForm)
+  TWLSFrm = class(TBasicStatsParamsForm)
     DepInBtn: TBitBtn;
     DepOutBtn: TBitBtn;
     IndInBtn: TBitBtn;
@@ -50,7 +50,7 @@ type
     procedure IndOutBtnClick(Sender: TObject);
     procedure IndVarListDblClick(Sender: TObject);
     procedure VarListDblClick(Sender: TObject);
-    procedure VarListSelectionChange(Sender: TObject; User: boolean);
+    procedure VarListSelectionChange(Sender: TObject; {%H-}User: boolean);
     procedure WghtInBtnClick(Sender: TObject);
     procedure WghtOutBtnClick(Sender: TObject);
 
@@ -64,18 +64,20 @@ type
 
     function GetPageCaption(AVarName: String): String;
 
+    procedure PlotSquaredResiduals(AIndepCols: IntDyneVec;
+      ANumIndepCols, ADepCol: Integer; AConfLevel: Double);
+
+    procedure PlotXY(AChartFrame: TChartFrame; const XPoints, YPoints: DblDyneVec;
+      const ARegressionResults: TBivariateRegressionResults; const XLabel, YLabel: String);
+
     procedure PredictIt(ColNoSelected: IntDyneVec; NoVars: integer;
       Means, StdDevs, BetaWeights: DblDyneVec;
       StdErrEst: double; NoIndepVars: integer);
 
-    procedure PlotXY(AChartFrame: TChartFrame; const XPoints, YPoints, UpConf, LowConf: DblDyneVec;
+    procedure WriteDescriptiveReport(AMemo: TMemo;
-      ConfBand, XMean, YMean, R, Slope, Intercept: Double; XLabel, YLabel: String);
+      const ARegressionResults: TBivariateRegressionResults;
+      const XLabel, YLabel: String);
 
-    procedure PlotXY(Xpoints, Ypoints, UpConf, LowConf: DblDyneVec;
-      ConfBand, Xmean, Ymean, R, Slope, Intercept: double;
-      Xmax,  Xmin, Ymax, Ymin: double;
-      N: integer; XLabel, YLabel: string);
-	
   protected
     procedure AdjustConstraints; override;
     procedure Compute; override;
@@ -97,15 +99,14 @@ implementation
 {$R *.lfm}
 
 uses
-  TAChartUtils, TALegend,
+  TAChartUtils, TAChartAxisUtils, TALegend, TASources, TACustomSeries,
-  Utils, GridProcs, MathUnit;
+  Utils, GridProcs;
 
 { TWLSFrm }
 
 constructor TWLSFrm.Create(AOwner: TComponent);
 begin
   inherited;
-  if BlankFrm = nil then Application.CreateForm(TBlankFrm, BlankFrm);
   if DictionaryFrm = nil then Application.CreateForm(TDictionaryFrm, DictionaryFrm);
 
   OLSReportFrame := TReportFrame.Create(self);
@@ -150,7 +151,7 @@ end;
 
 procedure TWLSFrm.Compute;
 var
-  i, ii, j, Noindep, DepCol, WghtCol, olddepcol, NCases, pos, col: integer;
+  i, j, Noindep, DepCol, WghtCol, olddepcol, NCases, pos, col: integer;
   IndepCols: IntDyneVec = nil;
   RowLabels: StrDyneVec = nil;
   X, Y: double;
@@ -163,24 +164,14 @@ var
   BtTests: DblDyneVec = nil;
   tProbs: DblDyneVec = nil;
   PrintDesc: boolean = true;
-  Xpoints: DblDyneVec = nil;
-  Ypoints: DblDyneVec = nil;
-  upConf: DblDyneVec = nil;
-  lowConf: DblDyneVec = nil;
-  Xmax, Xmin, Ymax, Ymin, Xmean, Ymean, Xvariance, Yvariance, R: double;
-  temp, SEPred, Slope, Intercept, DF, SSx, t, ConfBand, sedata: double;
-  Xstddev, Ystddev, predicted: double;
   ColNoSelected: IntDyneVec = nil;
-  XLabel, YLabel: string;
+  predicted: Double;
-  N, Xcol, Ycol, NoSelected: integer;
   lReport: TStrings;
   StdErrEst: Double = 0.0;
   R2: Double = 0.0;
   errorcode: Boolean = false;
   C: TWinControl;
   msg: String;
-  chartFrame: TChartFrame;
-  memo: TMemo;
 begin
   if not Validate(msg, C) then
   begin
@@ -201,10 +192,6 @@ begin
   SetLength(tprobs, NoVariables + 2);
   SetLength(RowLabels, NoVariables + 2);
   SetLength(IndepCols, NoVariables + 2);
-//  SetLength(Xpoints, NoCases + 1);
-//  SetLength(Ypoints, NoCases + 1);
-//  SetLength(UpConf, NoCases + 1);
-//  SetLength(lowConf, NoCases + 1);
   SetLength(ColNoSelected, 2);
 
   lReport := TStringList.Create;
@@ -298,11 +285,6 @@ begin
 
       OLSReportFrame.DisplayReport(lReport);
       lReport.Clear;
-      {
-      lReport.Add('');
-      lReport.Add(DIVIDER);
-      lReport.Add('');
-      }
     end;
 
     if RegResChk.Checked and OLSChk.Checked then
@@ -318,13 +300,6 @@ begin
 
       ResidualsRegReportFrame.DisplayReport(lReport);
       lReport.Clear;
-      {
-      lReport.Add(DIVIDER);
-      lReport.Add('');
-       }
-//      FReportFrame.DisplayReport(lReport);
-//      lReport.Clear;
-
     end;
 
     if WeightChk.Checked and RegResChk.Checked then
@@ -366,135 +341,9 @@ begin
       end; // next i
     end; // if regresChk
 
-    // Now, plot squared residuals against each independent variable
+    // Display squared residuals for each independent variable
     if RegResChk.Checked then
-    begin
+      PlotSquaredResiduals(IndepCols, NoIndep, DepCol, 0.95);
-      xCol := DepCol;
-      for ii := 0 to NoIndep - 1 do
-      begin
-        SetLength(xPoints, NoCases);
-        SetLength(yPoints, NoCases);
-        yCol := IndepCols[ii];
-        N := 0;
-        ColNoSelected[0] := xCol;
-        ColNoSelected[1] := yCol;
-        NoSelected := 2;
-        XLabel := OS3MainFrm.DataGrid.Cells[Xcol,0];
-        YLabel := OS3MainFrm.DataGrid.Cells[Ycol,0];
-        Xmax := -1.0e308;
-        Xmin := 1.0e308;
-        Ymax := -1.0e308;
-        Ymin := 1.0e308;
-        Xmean := 0.0;
-        Ymean := 0.0;
-        Xvariance := 0.0;
-        Yvariance := 0.0;
-        R := 0.0;
-        for i := 1 to NoCases do
-        begin
-          if (not DataProcs.GoodRecord(i,NoSelected,ColNoSelected)) then continue;
-          X := StrToFloat(OS3MainFrm.DataGrid.Cells[Xcol,i]);
-          Y := StrToFloat(OS3MainFrm.DataGrid.Cells[Ycol,i]);
-          Xpoints[N] := X;
-          Ypoints[N] := Y;
-          if (X > Xmax) then Xmax := X;
-          if (X < Xmin) then Xmin := X;
-          if (Y > Ymax) then Ymax := Y;
-          if (Y < Ymin) then Ymin := Y;
-          Xmean := Xmean + X;
-          Ymean := Ymean + Y;
-          Xvariance := Xvariance + X * X;
-          Yvariance := Yvariance + Y * Y;
-          R := R + X * Y;
-          N := N + 1;
-        end;
-        SetLength(xPoints, N);
-        SetLength(yPoints, N);
-
-        // sort on X
-        SortOnX(xPoints, yPoints);
-
-        // calculate statistics
-        Xvariance := Xvariance - Xmean * Xmean / N;
-        SSx := Xvariance;
-        Xvariance := Xvariance / (N - 1);
-        Xstddev := sqrt(Xvariance);
-
-        Yvariance := Yvariance - Ymean * Ymean / N;
-        Yvariance := Yvariance / (N - 1);
-        Ystddev := sqrt(Yvariance);
-
-        R := R - Xmean * Ymean / N;
-        R := R / (N - 1);
-        R := R / (Xstddev * Ystddev);
-
-        SEPred := sqrt(1.0 - R * R) * Ystddev;
-        SEPred := SEPred * sqrt((N - 1) / (N - 2));
-        Xmean := Xmean / N;
-        Ymean := Ymean / N;
-        Slope := R * Ystddev / Xstddev;
-        Intercept := Ymean - Slope * Xmean;
-
-        // Now, print the descriptive statistics if requested
-        lReport.Clear;
-        lReport.Add('Data file: %s', [OS3MainFrm.FileNameEdit.Text]);
-        lReport.Add('');
-        lReport.Add('Variables:');
-        lReport.Add('  X: %s', [OS3MainFrm.DataGrid.Cells[xCol, 0]]);
-        lReport.Add('  Y: %s', [OS3MainFrm.DataGrid.Cells[yCol, 0]]);
-        lReport.Add('');
-        lReport.Add('Variable      Mean    Variance  Std.Dev.');
-        lReport.Add('----------  --------  --------  --------');
-        lReport.Add('%-10s  %8.2f  %8.2f  %8.2f', [OS3MainFrm.DataGrid.Cells[xCol, 0], XMean, XVariance, XStdDev]);
-        lReport.Add('%-10s  %8.2f  %8.2f  %8.2f', [OS3MainFrm.DataGrid.Cells[ycol, 0], YMean, YVariance, YStdDev]);
-        lReport.Add('');
-        lReport.Add('Correlation:                %8.4f', [R]);
-        lReport.Add('Slope:                      %8.2f', [Slope]);
-        lReport.Add('Intercept:                  %8.2f', [Intercept]);
-        lReport.Add('Standard Error of Estimate: %8.2f', [SEPred]);
-        lReport.Add('Number of good cases:       %8d',   [N]);
-
-        // Get upper and lower confidence points for each X value
-        SetLength(UpConf, N);
-        SetLength(LowConf, N);
-        ConfBand := 0.95;
-        DF := N - 2;
-        t := inverset(ConfBand,DF);
-        for i := 0 to N-1 do
-        begin
-          X := Xpoints[i];
-          predicted := Slope * X + Intercept;
-          sedata := SEPred * sqrt(1.0 + (1.0 / N) + ((X - Xmean) * (X - Xmean) / SSx));
-          UpConf[i] := predicted + (t * sedata);
-          lowConf[i] := predicted - (t * sedata);
-          if (UpConf[i] > Ymax) then Ymax := UpConf[i];
-          if (lowConf[i] < Ymin) then Ymin := lowConf[i];
-        end;
-
-        // Plot the values, line and confidence band
-        CreateOrGetChartFrame(yCol, yLabel, memo, chartFrame);
-        chartFrame.Clear;
-        PlotXY(chartFrame, XPoints, YPoints, upConf, lowConf, confBand, xMean, yMean, R, slope, intercept, xLabel, yLabel);
-        memo.Lines.Assign(lReport);
-        lReport.Clear;
-        {
-        if NormPltChk.Checked then
-          PlotNormalDist(chartFrame, normDistValue);
-        PlotFreq(chartFrame, col, cellVal, xLabels, freq);
-        }
-
-
-
-        if PlotChk.Checked then
-        begin
-          PlotXY(Xpoints, Ypoints, UpConf, lowConf, ConfBand, Xmean, Ymean, R,
-                 Slope, Intercept, Xmax, Xmin, Ymax, Ymin, N, XLabel, YLabel);
-          BlankFrm.ShowModal;
-        end;
-      end;
-
- //     FReportFrame.DisplayReport(lReport);
-    end;
 
     if not UserWghtsChk.Checked then
     begin
@@ -516,7 +365,7 @@ begin
       // get means of variables and subtract from the values
       if OriginChk.Checked then
       begin
-        for j := 0 to Noindep do
+        for j := 0 to NoIndep do
         begin
           Means[j] := 0.0;
           NCases := 0;
@@ -647,6 +496,22 @@ begin
   AChartFrame.Chart.Legend.TextFormat := tfHTML;
   AChartFrame.Chart.BottomAxis.Intervals.MaxLength := 80;
   AChartFrame.Chart.BottomAxis.Intervals.MinLength := 30;
+  with AChartFrame.Chart.AxisList.Add do
+  begin
+    Alignment := calRight;
+    Marks.Source := TListChartSource.Create(self);
+    Marks.Style := smsLabel;
+    Grid.Visible := false;
+    TickColor := clNone;
+  end;
+  with AChartFrame.Chart.AxisList.Add do
+  begin
+    Alignment := calTop;
+    Marks.Source := TListChartSource.Create(self);
+    Marks.Style := smsLabel;
+    Grid.Visible := false;
+    TickColor := clNone;
+  end;
 
   // ... and add memo
   AMemo := TMemo.Create(tabSheet);
@@ -749,6 +614,116 @@ begin
   end;
 end;
 
+
+procedure TWLSFrm.PlotSquaredResiduals(AIndepCols: IntDyneVec;
+  ANumIndepCols, ADepCol: Integer; AConfLevel: Double);
+var
+  xCol, yCol: Integer;
+  xLabel, yLabel: String;
+  i: Integer;
+  colNoSelected: IntDyneVec = nil;
+  xPoints: DblDyneVec = nil;
+  yPoints: DblDyneVec = nil;
+  regressionRes: TBivariateRegressionResults;
+  memo: TMemo;
+  chartFrame: TChartFrame;
+begin
+  SetLength(colNoSelected, 2);
+  xCol := ADepCol;
+
+  for i := 0 to ANumIndepCols-1 do
+  begin
+    // Get values
+    yCol := AIndepCols[i];
+    colNoSelected[0] := xCol;
+    colNoSelected[1] := yCol;
+    xLabel := OS3MainFrm.DataGrid.Cells[xCol, 0];
+    yLabel := OS3MainFrm.DataGrid.Cells[yCol, 0];
+    xPoints := CollectValues(OS3MainFrm.DataGrid, xCol, colNoSelected);
+    yPoints := CollectValues(OS3MainFrm.DataGrid, yCol, colNoSelected);
+    SortOnX(xPoints, yPoints);
+
+    // Regression
+    Calc_BivariateRegression(xPoints, yPoints, AConfLevel, regressionRes);
+
+    // Create tab with chart and report controls
+    CreateOrGetChartFrame(yCol, yLabel, memo, chartFrame);
+
+    // Plot
+    PlotXY(chartFrame, xPoints, yPoints, regressionRes, xLabel, yLabel);
+
+    // Print the descriptive statistics
+    WriteDescriptiveReport(memo, regressionRes, xLabel, yLabel);
+  end;
+end;
+
+
+procedure TWLSFrm.PlotXY(AChartFrame: TChartFrame; const XPoints, YPoints: DblDyneVec;
+  const ARegressionResults: TBivariateRegressionResults; const XLabel, YLabel: String);
+var
+  xpts: DblDyneVec = nil;
+  ypts: DblDyneVec = nil;
+  conf: DblDyneVec = nil;
+  ext: TDoubleRect;
+  i: Integer;
+  rightLabels, topLabels: TListChartSource;
+  ser: TChartSeries;
+begin
+  rightLabels := AChartFrame.Chart.AxisList[2].Marks.Source as TListChartSource;
+  rightLabels.Clear;
+  topLabels := AChartFrame.Chart.AxisList[3].Marks.Source as TListChartSource;
+  topLabels.Clear;
+  AChartFrame.Clear;
+
+  with ARegressionResults do
+    AChartFrame.SetFooter(Format('R(X,Y) = %.3f, Slope = %.3f, Intercept = %.3f', [
+      R, Slope, Intercept
+    ]));
+
+  // Data points
+  AChartFrame.SetXTitle(XLabel);
+  AChartFrame.SetYTitle(YLabel);
+  AChartFrame.PlotXY(ptSymbols, XPoints, YPoints, nil, nil, 'Data', DATA_COLORS[0]);
+
+  // Regression line
+  SetLength(xpts, 2);
+  SetLengtH(ypts, 2);
+  ext := AChartFrame.Chart.GetFullExtent;
+  xpts[0] := ext.a.x;
+  xpts[1] := ext.b.x;
+  with ARegressionResults do
+  begin
+    ypts[0] := Intercept + Slope * xpts[0];
+    ypts[1] := Intercept + Slope * xpts[1];
+  end;
+  AChartFrame.PlotXY(ptLines, xpts, ypts, nil, nil, 'Predicted', clBlack);
+  rightLabels.Add(ypts[1], ypts[1], 'Predicted');
+
+  // Upper ...
+  SetLength(conf, ARegressionResults.Count);
+  for i := 0 to High(conf) do
+    conf[i] := ARegressionResults.ConfidenceLimits(XPoints[i], true);
+  ser := AChartFrame.PlotXY(ptLines, XPoints, conf, nil, nil, 'Upper confidence band', clRed);
+  rightLabels.Add(ser.yValue[ser.Count-1], ser.yValue[ser.Count-1], 'UCL');
+
+  // ... and lower confidence limit curves
+  for i := 0 to High(conf) do
+    conf[i] := ARegressionResults.ConfidenceLimits(XPoints[i], false);
+  ser := AChartFrame.PlotXY(ptLines, XPoints, conf, nil, nil, 'Lower confidence band', clRed);
+  rightLabels.Add(ser.yValue[ser.Count-1], ser.yValue[ser.Count-1], 'LCL');
+
+  // Mean lines
+  with ARegressionResults do
+  begin
+    AChartFrame.VertLine(XMean, clGreen, psDashDot, 'Mean ' + XLabel);
+    topLabels.Add(XMean, XMean, 'Mean ' + XLabel);
+
+    AChartFrame.HorLine(YMean, clGreen, psDash, 'Mean ' + YLabel);
+    rightLabels.Add(YMean, YMean, 'Mean ' + YLabel);
+  end;
+end;
+
+
 { Routine obtains predicted raw and standardized scores and their
   residuals.  It is assumed that the dependent variable is last in the
   list of variable column pointers stored in the ColNoSelected vector.
@@ -837,230 +812,6 @@ begin
 end;
 
 
-procedure TWLSFrm.PlotXY(AChartFrame: TChartFrame;
-  const XPoints, YPoints, UpConf, LowConf: DblDyneVec;
-  ConfBand, XMean, YMean, R, Slope, Intercept: Double; XLabel, YLabel: String);
-var
-  xpts: DblDyneVec = nil;
-  ypts: DblDyneVec = nil;
-  ext: TDoubleRect;
-begin
-  AChartFrame.SetFooter(Format('R(X,Y) = %.3f, Slope = %.3f, Intercept = %.3f', [
-    R, Slope, Intercept
-  ]));
-
-  // Data points
-  AChartFrame.SetXTitle(XLabel);
-  AChartFrame.SetYTitle(YLabel);
-  AChartFrame.PlotXY(ptSymbols, XPoints, YPoints, nil, nil, 'Data', DATA_COLORS[0]);
-
-  // Regression line
-  SetLength(xpts, 2);
-  SetLengtH(ypts, 2);
-  ext := AChartFrame.Chart.GetFullExtent;
-  xpts[0] := ext.a.x;
-  xpts[0] := ext.b.x;
-  ypts[0] := Intercept + Slope * xpts[0];
-  ypts[1] := Intercept + Slope * xpts[1];
-  AChartFrame.PlotXY(ptLines, xpts, ypts, nil, nil, 'Predicted', clBlack);
-
-  // Upper and lower confidence limit curves
-  AChartFrame.PlotXY(ptLines, XPoints, UpConf, nil, nil, 'UCL', clRed);
-  AChartFrame.PlotXY(ptLines, XPoints, LowConf, nil, nil, 'LCL', clRed);
-
-  // Mean lines
-  AChartFrame.VertLine(XMean, clGreen, psDashDot, 'Mean ' + XLabel);
-//  topLabels.Add(XMean, XMean, 'Mean ' + XLabel);
-
-  AChartFrame.HorLine(YMean, clGreen, psDash, 'Mean ' + YLabel);
-//  rightLabels.Add(YMean, YMean, 'Mean ' + YLabel);
-end;
-
-
-procedure TWLSFrm.PlotXY(Xpoints, Ypoints, UpConf, LowConf : DblDyneVec;
-                        ConfBand, Xmean, Ymean, R, Slope, Intercept : double;
-                        Xmax,  Xmin, Ymax, Ymin : double;
-                        N : integer; XLabel, YLabel : string);
-VAR
-     i, xpos, ypos, hleft, hright, vtop, vbottom, imagewide : integer;
-     vhi, hwide, offset, strhi, imagehi : integer;
-     valincr, Yvalue, Xvalue, value : double;
-     Title, outline : string;
-
-begin
-     BlankFrm.Image1.Canvas.Clear;
-     Title := 'X versus Y PLOT Using File: ' + OS3MainFrm.FileNameEdit.Text;
-     BlankFrm.Caption := Title;
-     imagewide := BlankFrm.Image1.Width;
-     imagehi := BlankFrm.Image1.Height;
-     BlankFrm.Image1.Canvas.Pen.Color := clBlack;
-     BlankFrm.Image1.Canvas.Brush.Color := clWhite;
-     BlankFrm.Image1.Canvas.Rectangle(0,0,imagewide,imagehi);
-     BlankFrm.Image1.Canvas.FloodFill(0,0,clWhite,fsBorder);
-     vtop := 20;
-     vbottom := round(imagehi) - 80;
-     vhi := vbottom - vtop;
-     hleft := 100;
-     hright := imagewide - 80;
-     hwide := hright - hleft;
-     BlankFrm.Image1.Canvas.Pen.Color := clBlack;
-     BlankFrm.Image1.Canvas.Brush.Color := clWhite;
-
-     // Draw chart border
-     BlankFrm.Image1.Canvas.Rectangle(0,0,imagewide,imagehi);
-
-     // draw Means
-          ypos := round(vhi * ( (Ymax - Ymean) / (Ymax - Ymin)));
-          ypos := ypos + vtop;
-          xpos := hleft;
-          BlankFrm.Image1.Canvas.MoveTo(xpos,ypos);
-          xpos := hright;
-          BlankFrm.Image1.Canvas.Pen.Color := clGreen;
-          BlankFrm.Image1.Canvas.LineTo(xpos,ypos);
-          Title := 'MEAN ';
-          Title := Title + YLabel;
-          strhi := BlankFrm.Image1.Canvas.TextHeight(Title);
-          ypos := ypos - strhi div 2;
-          BlankFrm.Image1.Canvas.Brush.Color := clWhite;
-          BlankFrm.Image1.Canvas.TextOut(xpos,ypos,Title);
-
-          xpos := round(hwide * ( (Xmean - Xmin) / (Xmax - Xmin)));
-          xpos := xpos + hleft;
-          ypos := vtop;
-          BlankFrm.Image1.Canvas.MoveTo(xpos,ypos);
-          ypos := vbottom;
-          BlankFrm.Image1.Canvas.Pen.Color := clGreen;
-          BlankFrm.Image1.Canvas.LineTo(xpos,ypos);
-          Title := 'MEAN ';
-          Title := Title + XLabel;
-          strhi := BlankFrm.Image1.Canvas.TextWidth(Title);
-          xpos := xpos - strhi div 2;
-          ypos := vtop - BlankFrm.Image1.Canvas.TextHeight(Title);
-          BlankFrm.Image1.Canvas.Brush.Color := clWhite;
-          BlankFrm.Image1.Canvas.TextOut(xpos,ypos,Title);
-
-     // draw slope line
-          BlankFrm.Image1.Canvas.Pen.Color := clBlack;
-          Yvalue := (Xpoints[1] * Slope) + Intercept; // predicted score
-          ypos := round(vhi * ( (Ymax - Yvalue) / (Ymax - Ymin)));
-          ypos := ypos + vtop;
-          xpos := round(hwide * ( (Xpoints[1]- Xmin) / (Xmax - Xmin)));
-          xpos := xpos + hleft;
-          BlankFrm.Image1.Canvas.MoveTo(xpos,ypos);
-          Yvalue := (Xpoints[N] * Slope) + Intercept; // predicted score
-          ypos := round(vhi * ( (Ymax - Yvalue) / (Ymax - Ymin)));
-          ypos := ypos + vtop;
-          xpos := round(hwide * ( (Xpoints[N] - Xmin) / (Xmax - Xmin)));
-          xpos := xpos + hleft;
-          BlankFrm.Image1.Canvas.LineTo(xpos,ypos);
-
-     // draw horizontal axis
-     BlankFrm.Image1.Canvas.Pen.Color := clBlack;
-     BlankFrm.Image1.Canvas.MoveTo(hleft,vbottom);
-     BlankFrm.Image1.Canvas.LineTo(hright,vbottom);
-     valincr := (Xmax - Xmin) / 10.0;
-     for i := 1 to 11 do
-     begin
-          ypos := vbottom;
-          Xvalue := Xmin + valincr * (i - 1);
-          xpos := round(hwide * ((Xvalue - Xmin) / (Xmax - Xmin)));
-          xpos := xpos + hleft;
-          BlankFrm.Image1.Canvas.MoveTo(xpos,ypos);
-          ypos := ypos + 10;
-          BlankFrm.Image1.Canvas.LineTo(xpos,ypos);
-          outline := format('%6.2f',[Xvalue]);
-          Title := outline;
-          offset := BlankFrm.Image1.Canvas.TextWidth(Title) div 2;
-          xpos := xpos - offset;
-          BlankFrm.Image1.Canvas.Pen.Color := clBlack;
-          BlankFrm.Image1.Canvas.TextOut(xpos,ypos,Title);
-     end;
-     xpos := hleft + (hwide div 2) - (BlankFrm.Image1.Canvas.TextWidth(XLabel) div 2);
-     ypos := vbottom + 20;
-     BlankFrm.Image1.Canvas.TextOut(xpos,ypos,XLabel);
-     outline := format('R(X,Y) := %5.3f, Slope := %6.2f, Intercept := %6.2f',
-              [R,Slope,Intercept]);
-     Title := outline;
-     xpos := hleft + (hwide div 2) - (BlankFrm.Image1.Canvas.TextWidth(Title) div 2);
-     ypos := ypos + 15;
-     BlankFrm.Image1.Canvas.TextOut(xpos,ypos,Title);
-
-     // Draw vertical axis
-     Title := YLabel;
-//     xpos := hleft - 10 - BlankFrm.Image1.Canvas.TextWidth(Title) / 2;
-     xpos := 10;
-     ypos := vtop - 8 - BlankFrm.Image1.Canvas.TextHeight(Title);
-     BlankFrm.Image1.Canvas.TextOut(xpos,ypos,YLabel);
-     xpos := hleft;
-     ypos := vtop;
-     BlankFrm.Image1.Canvas.MoveTo(xpos,ypos);
-     ypos := vbottom;
-     BlankFrm.Image1.Canvas.LineTo(xpos,ypos);
-     valincr := (Ymax - Ymin) / 10.0;
-     for i := 1 to 11 do
-     begin
-          value := Ymax - ((i-1) * valincr);
-          outline := format('%8.2f',[value]);
-          Title := outline;
-          strhi := BlankFrm.Image1.Canvas.TextHeight(Title);
-          xpos := 10;
-          Yvalue := Ymax - (valincr * (i-1));
-          ypos := round(vhi * ( (Ymax - Yvalue) / (Ymax - Ymin)));
-          ypos := ypos + vtop - strhi div 2;
-          BlankFrm.Image1.Canvas.TextOut(xpos,ypos,Title);
-          xpos := hleft;
-          ypos := ypos + strhi div 2;
-          BlankFrm.Image1.Canvas.MoveTo(xpos,ypos);
-          xpos := hleft - 10;
-          BlankFrm.Image1.Canvas.LineTo(xpos,ypos);
-     end;
-
-     // draw points for x and y pairs
-     for i := 0 to N-1 do
-     begin
-          ypos := round(vhi * ( (Ymax - Ypoints[i]) / (Ymax - Ymin)));
-          ypos := ypos + vtop;
-          xpos := round(hwide * ( (Xpoints[i] - Xmin) / (Xmax - Xmin)));
-          xpos := xpos + hleft;
-          BlankFrm.Image1.Canvas.Brush.Color := clNavy;
-          BlankFrm.Image1.Canvas.Brush.Style := bsSolid;
-          BlankFrm.Image1.Canvas.Pen.Color := clNavy;
-          BlankFrm.Image1.Canvas.Ellipse(xpos,ypos,xpos+5,ypos+5);
-     end;
-
-     // draw confidence bands if requested
-     if not (ConfBand = 0.0) then
-     begin
-          BlankFrm.Image1.Canvas.Pen.Color := clRed;
-          ypos := round(vhi * ((Ymax - UpConf[0]) / (Ymax - Ymin)));
-          ypos := ypos + vtop;
-          xpos := round(hwide * ( (Xpoints[0] - Xmin) / (Xmax - Xmin)));
-          xpos := xpos + hleft;
-          BlankFrm.Image1.Canvas.MoveTo(xpos,ypos);
-          for i := 1 to N-1 do
-          begin
-               ypos := round(vhi * ((Ymax - UpConf[i]) / (Ymax - Ymin)));
-               ypos := ypos + vtop;
-               xpos := round(hwide * ( (Xpoints[i] - Xmin) / (Xmax - Xmin)));
-               xpos := xpos + hleft;
-               BlankFrm.Image1.Canvas.LineTo(xpos,ypos);
-          end;
-          ypos := round(vhi * ((Ymax - LowConf[0]) / (Ymax - Ymin)));
-          ypos := ypos + vtop;
-          xpos := round(hwide * ( (Xpoints[0] - Xmin) / (Xmax - Xmin)));
-          xpos := xpos + hleft;
-          BlankFrm.Image1.Canvas.MoveTo(xpos,ypos);
-          for i := 1 to N-1 do
-          begin
-               ypos := round(vhi * ((Ymax - LowConf[i]) / (Ymax - Ymin)));
-               ypos := ypos + vtop;
-               xpos := round(hwide * ( (Xpoints[i] - Xmin) / (Xmax - Xmin)));
-               xpos := xpos + hleft;
-               BlankFrm.Image1.Canvas.LineTo(xpos,ypos);
-          end;
-     end;
-end;
-
 procedure TWLSFrm.Reset;
 var
   i: integer;
@@ -1191,5 +942,41 @@ begin
   UpdateBtnStates;
 end;
 
+
+procedure TWLSFrm.WriteDescriptiveReport(AMemo: TMemo;
+  const ARegressionResults: TBivariateRegressionResults;
+  const XLabel, YLabel: String);
+var
+  lReport: TStrings;
+begin
+  lReport := TStringList.Create;
+  try
+    lReport.Add('Data file: %s', [OS3MainFrm.FileNameEdit.Text]);
+    lReport.Add('');
+    lReport.Add('Variables:');
+    lReport.Add('  X: %s', [xLabel]);
+    lReport.Add('  Y: %s', [yLabel]);
+    lReport.Add('');
+    lReport.Add('Variable      Mean    Variance  Std.Dev.');
+    lReport.Add('----------  --------  --------  --------');
+    with ARegressionResults do
+    begin
+      lReport.Add('%-10s  %8.2f  %8.2f  %8.2f', [xLabel, XMean, XVariance, XStdDev]);
+      lReport.Add('%-10s  %8.2f  %8.2f  %8.2f', [yLabel, YMean, YVariance, YStdDev]);
+      lReport.Add('');
+      lReport.Add('Regression:');
+      lReport.Add('  Correlation:                %8.3f', [R]);
+      lReport.Add('  Slope:                      %8.3f', [Slope]);
+      lReport.Add('  Intercept:                  %8.3f', [Intercept]);
+      lReport.Add('  Standard Error of Estimate: %8.3f', [StdErrorPredicted]);
+      lReport.Add('  Number of good cases:       %8d',   [Count]);
+    end;
+    AMemo.Lines.Assign(lReport);
+  finally
+    lReport.Free;
+  end;
+end;
+
+
 end.