LazStats: More refactoring in CompareDistUnit.

git-svn-id: https://svn.code.sf.net/p/lazarus-ccr/svn@7722 8e941d3f-bd1b-0410-a28a-d453659cc2b4

applications/lazstats/source/LazStats.lpi

@@ -1,11 +1,13 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <CONFIG>
   <ProjectOptions>
-    <Version Value="11"/>
+    <Version Value="12"/>
     <PathDelim Value="\"/>
     <General>
+      <Flags>
+        <CompatibilityMode Value="True"/>
+      </Flags>
       <SessionStorage Value="InProjectDir"/>
-      <MainUnit Value="0"/>
       <Scaled Value="True"/>
       <UseXPManifest Value="True"/>
       <XPManifest>
@@ -93,7 +95,6 @@
     </PublishOptions>
     <RunParams>
       <FormatVersion Value="2"/>
-      <Modes Count="0"/>
     </RunParams>
     <RequiredPackages Count="7">
       <Item1>

applications/lazstats/source/forms/analysis/descriptive/comparedistunit.lfm

@@ -1,19 +1,19 @@
 inherited CompareDistFrm: TCompareDistFrm
-  Left = 671
+  Left = 459
-  Height = 413
+  Height = 504
-  Top = 327
+  Top = 178
   Width = 924
   HelpType = htKeyword
   HelpKeyword = 'html/ComparisonsWithTheoreticalDistri.htm'
   Caption = 'Compare Cumulative Distributions'
-  ClientHeight = 413
+  ClientHeight = 504
   ClientWidth = 924
   OnActivate = FormActivate
   OnCreate = FormCreate
   Position = poMainFormCenter
   object ParamsPanel: TPanel[0]
     Left = 8
-    Height = 397
+    Height = 488
     Top = 8
     Width = 288
     Align = alLeft
@@ -22,7 +22,7 @@ inherited CompareDistFrm: TCompareDistFrm
     BorderSpacing.Right = 4
     BorderSpacing.Bottom = 8
     BevelOuter = bvNone
-    ClientHeight = 397
+    ClientHeight = 488
     ClientWidth = 288
     TabOrder = 0
     object ResetBtn: TButton
@@ -31,7 +31,7 @@ inherited CompareDistFrm: TCompareDistFrm
       AnchorSideBottom.Side = asrBottom
       Left = 87
       Height = 25
-      Top = 372
+      Top = 463
       Width = 54
       Anchors = [akRight, akBottom]
       AutoSize = True
@@ -47,7 +47,7 @@ inherited CompareDistFrm: TCompareDistFrm
       AnchorSideBottom.Side = asrBottom
       Left = 149
       Height = 25
-      Top = 372
+      Top = 463
       Width = 76
       Anchors = [akRight, akBottom]
       AutoSize = True
@@ -65,7 +65,7 @@ inherited CompareDistFrm: TCompareDistFrm
       AnchorSideBottom.Side = asrBottom
       Left = 233
       Height = 25
-      Top = 372
+      Top = 463
       Width = 55
       Anchors = [akRight, akBottom]
       AutoSize = True
@@ -83,7 +83,7 @@ inherited CompareDistFrm: TCompareDistFrm
       AnchorSideBottom.Control = ResetBtn
       Left = 0
       Height = 8
-      Top = 356
+      Top = 447
       Width = 288
       Anchors = [akLeft, akRight, akBottom]
       Shape = bsBottomLine
@@ -93,14 +93,14 @@ inherited CompareDistFrm: TCompareDistFrm
       AnchorSideBottom.Control = Bevel1
       Left = 0
       Height = 83
-      Top = 273
+      Top = 364
-      Width = 302
+      Width = 298
       Anchors = [akLeft, akBottom]
       AutoSize = True
       BorderSpacing.Top = 8
       Caption = 'Option:'
       ClientHeight = 63
-      ClientWidth = 298
+      ClientWidth = 294
       TabOrder = 3
       object BothChk: TCheckBox
         AnchorSideLeft.Control = OptionsGroup
@@ -108,15 +108,15 @@ inherited CompareDistFrm: TCompareDistFrm
         Left = 16
         Height = 19
         Top = 6
-        Width = 270
+        Width = 266
         BorderSpacing.Left = 16
         BorderSpacing.Top = 6
         BorderSpacing.Right = 12
         BorderSpacing.Bottom = 8
-        Caption = 'Plot both Frequency and cumulative Frequency'
+        Caption = 'Plot both frequency and cumulative frequency'
         TabOrder = 0
       end
-      object VertBarBtn: TSpeedButton
+      object BarPlotBtn: TSpeedButton
         AnchorSideLeft.Control = OptionsGroup
         AnchorSideTop.Control = BothChk
         AnchorSideTop.Side = asrBottom
@@ -126,35 +126,25 @@ inherited CompareDistFrm: TCompareDistFrm
         Width = 23
         BorderSpacing.Left = 16
         BorderSpacing.Bottom = 8
+        Down = True
+        GroupIndex = 1
         Images = MainDataModule.ImageList
         ImageIndex = 8
       end
       object LinePlotBtn: TSpeedButton
-        AnchorSideLeft.Control = VertBarBtn
+        AnchorSideLeft.Control = BarPlotBtn
         AnchorSideLeft.Side = asrBottom
-        AnchorSideTop.Control = VertBarBtn
+        AnchorSideTop.Control = BarPlotBtn
         AnchorSideTop.Side = asrCenter
         Left = 43
         Height = 22
         Top = 33
         Width = 23
         BorderSpacing.Left = 4
+        GroupIndex = 1
         Images = MainDataModule.ImageList
         ImageIndex = 10
       end
-      object ThreeDChk: TCheckBox
-        AnchorSideLeft.Control = LinePlotBtn
-        AnchorSideLeft.Side = asrBottom
-        AnchorSideTop.Control = VertBarBtn
-        AnchorSideTop.Side = asrCenter
-        Left = 82
-        Height = 19
-        Top = 35
-        Width = 34
-        BorderSpacing.Left = 16
-        Caption = '3D'
-        TabOrder = 1
-      end
     end
     object Label1: TLabel
       AnchorSideLeft.Control = ParamsPanel
@@ -173,7 +163,7 @@ inherited CompareDistFrm: TCompareDistFrm
       AnchorSideRight.Control = Var1InBtn
       AnchorSideBottom.Control = OptionsGroup
       Left = 0
-      Height = 248
+      Height = 339
       Top = 17
       Width = 99
       Anchors = [akTop, akLeft, akRight, akBottom]
@@ -287,49 +277,155 @@ inherited CompareDistFrm: TCompareDistFrm
       AnchorSideRight.Control = CompareGroup
       AnchorSideRight.Side = asrBottom
       Left = 105
-      Height = 60
+      Height = 191
       Top = 165
       Width = 183
-      PageIndex = 1
+      PageIndex = 0
       AutoSize = True
       Anchors = [akTop, akLeft, akRight]
       BorderSpacing.Bottom = 8
       TabOrder = 9
       object TheoreticalDistPage: TPage
-        object DistGroup: TRadioGroup
+        object DistGroup: TGroupBox
           AnchorSideLeft.Control = TheoreticalDistPage
           AnchorSideTop.Control = TheoreticalDistPage
           AnchorSideRight.Control = TheoreticalDistPage
           AnchorSideRight.Side = asrBottom
           Left = 0
-          Height = 139
+          Height = 191
-          Top = 16
+          Top = 0
           Width = 183
           Anchors = [akTop, akLeft, akRight]
-          AutoFill = True
           AutoSize = True
-          BorderSpacing.Top = 16
+          Caption = 'Theoretical Distribution'
-          Caption = 'Theoretical Distributions:'
+          ClientHeight = 171
-          ChildSizing.LeftRightSpacing = 18
-          ChildSizing.TopBottomSpacing = 8
-          ChildSizing.VerticalSpacing = 2
-          ChildSizing.EnlargeHorizontal = crsHomogenousChildResize
-          ChildSizing.EnlargeVertical = crsHomogenousChildResize
-          ChildSizing.ShrinkHorizontal = crsScaleChilds
-          ChildSizing.ShrinkVertical = crsScaleChilds
-          ChildSizing.Layout = cclLeftToRightThenTopToBottom
-          ChildSizing.ControlsPerLine = 1
-          ClientHeight = 119
           ClientWidth = 179
-          Items.Strings = (
-            'Normal Distribution'
-            't-Distribution'
-            'Chi-Sq Distribution'
-            'F Distribution'
-            'Poisson Distribution'
-          )
-          OnClick = DistGroupClick
           TabOrder = 0
+          object NormalDistChk: TRadioButton
+            AnchorSideLeft.Control = DistGroup
+            AnchorSideTop.Control = DistGroup
+            Left = 16
+            Height = 19
+            Top = 2
+            Width = 125
+            BorderSpacing.Left = 16
+            BorderSpacing.Top = 2
+            BorderSpacing.Right = 16
+            Caption = 'Normal Distribution'
+            OnChange = DistChange
+            TabOrder = 0
+          end
+          object tDistChk: TRadioButton
+            AnchorSideLeft.Control = NormalDistChk
+            AnchorSideTop.Control = NormalDistChk
+            AnchorSideTop.Side = asrBottom
+            Left = 16
+            Height = 19
+            Top = 23
+            Width = 89
+            BorderSpacing.Top = 2
+            Caption = 't Distribution'
+            OnChange = DistChange
+            TabOrder = 1
+          end
+          object ChiSqDistChk: TRadioButton
+            AnchorSideLeft.Control = NormalDistChk
+            AnchorSideTop.Control = tDistChk
+            AnchorSideTop.Side = asrBottom
+            Left = 16
+            Height = 19
+            Top = 44
+            Width = 121
+            BorderSpacing.Top = 2
+            BorderSpacing.Right = 12
+            Caption = 'Chi-Sq Distribution'
+            OnChange = DistChange
+            TabOrder = 2
+          end
+          object FDistChk: TRadioButton
+            AnchorSideLeft.Control = NormalDistChk
+            AnchorSideTop.Control = ChiSqDistChk
+            AnchorSideTop.Side = asrBottom
+            Left = 16
+            Height = 19
+            Top = 65
+            Width = 91
+            BorderSpacing.Top = 2
+            Caption = 'F Distribution'
+            OnChange = DistChange
+            TabOrder = 3
+          end
+          object PoissonDistChk: TRadioButton
+            AnchorSideLeft.Control = NormalDistChk
+            AnchorSideTop.Control = FDistChk
+            AnchorSideTop.Side = asrBottom
+            Left = 16
+            Height = 19
+            Top = 86
+            Width = 126
+            BorderSpacing.Top = 2
+            BorderSpacing.Right = 12
+            BorderSpacing.Bottom = 8
+            Caption = 'Poisson Distribution'
+            OnChange = DistChange
+            TabOrder = 4
+          end
+          object DF1Label: TLabel
+            AnchorSideTop.Control = DF1Edit
+            AnchorSideTop.Side = asrCenter
+            AnchorSideRight.Control = DF1Edit
+            Left = 48
+            Height = 15
+            Top = 117
+            Width = 29
+            Anchors = [akTop, akRight]
+            BorderSpacing.Right = 8
+            Caption = 'D.F. 1'
+            ParentColor = False
+          end
+          object DF1Edit: TEdit
+            AnchorSideTop.Control = PoissonDistChk
+            AnchorSideTop.Side = asrBottom
+            AnchorSideRight.Control = DistGroup
+            AnchorSideRight.Side = asrBottom
+            Left = 85
+            Height = 23
+            Top = 113
+            Width = 82
+            Anchors = [akTop, akRight]
+            BorderSpacing.Right = 12
+            BorderSpacing.Bottom = 4
+            TabOrder = 5
+            Text = 'DF1Edit'
+          end
+          object DF2Edit: TEdit
+            AnchorSideLeft.Control = DF1Edit
+            AnchorSideTop.Control = DF1Edit
+            AnchorSideTop.Side = asrBottom
+            AnchorSideRight.Control = DF1Edit
+            AnchorSideRight.Side = asrBottom
+            Left = 85
+            Height = 23
+            Top = 140
+            Width = 82
+            Anchors = [akTop, akLeft, akRight]
+            BorderSpacing.Bottom = 8
+            TabOrder = 6
+            Text = 'DF2Edit'
+          end
+          object DF2Label: TLabel
+            AnchorSideTop.Control = DF2Edit
+            AnchorSideTop.Side = asrCenter
+            AnchorSideRight.Control = DF2Edit
+            Left = 48
+            Height = 15
+            Top = 144
+            Width = 29
+            Anchors = [akTop, akRight]
+            BorderSpacing.Right = 8
+            Caption = 'D.F. 2'
+            ParentColor = False
+          end
         end
       end
       object VariablePage: TPage
@@ -396,27 +492,30 @@ inherited CompareDistFrm: TCompareDistFrm
   end
   object PageControl1: TPageControl[1]
     Left = 309
-    Height = 397
+    Height = 488
     Top = 8
     Width = 607
-    ActivePage = ReportPage
+    ActivePage = CumFreqChartPage
     Align = alClient
     BorderSpacing.Left = 4
     BorderSpacing.Top = 8
     BorderSpacing.Right = 8
     BorderSpacing.Bottom = 8
-    TabIndex = 0
+    TabIndex = 1
     TabOrder = 1
     object ReportPage: TTabSheet
       Caption = 'Report'
     end
-    object ChartPage: TTabSheet
+    object CumFreqChartPage: TTabSheet
-      Caption = 'Chart'
+      Caption = 'Cumulative frequency plot'
+    end
+    object FreqChartPage: TTabSheet
+      Caption = 'Frequency plot'
     end
   end
   object ParamsSplitter: TSplitter[2]
     Left = 300
-    Height = 413
+    Height = 504
     Top = 0
     Width = 5
     ResizeStyle = rsPattern

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

@@ -13,18 +13,30 @@ uses
   BasicStatsFormUnit, ReportFrameUnit, ChartFrameUnit;
 
 type
+  TCompareTo = (ctTheoreticalDistrib, ctVariable);
+  TCompareDist = (cd_Normal, cd_t, cd_ChiSq, cd_F, cd_Poisson);
 
   { TCompareDistFrm }
 
   TCompareDistFrm = class(TBasicStatsForm)
     Bevel1: TBevel;
+    DF1Edit: TEdit;
+    DF2Edit: TEdit;
+    DistGroup: TGroupBox;
+    DF1Label: TLabel;
+    DF2Label: TLabel;
     PageControl1: TPageControl;
     ParamsSplitter: TSplitter;
+    NormalDistChk: TRadioButton;
+    FreqChartPage: TTabSheet;
+    tDistChk: TRadioButton;
+    ChiSqDistChk: TRadioButton;
+    FDistChk: TRadioButton;
+    PoissonDistChk: TRadioButton;
     ReportPage: TTabSheet;
-    ChartPage: TTabSheet;
+    CumFreqChartPage: TTabSheet;
-    ThreeDChk: TCheckBox;
     Notebook: TNotebook;
-    VertBarBtn: TSpeedButton;
+    BarPlotBtn: TSpeedButton;
     LinePlotBtn: TSpeedButton;
     TheoreticalDistPage: TPage;
     VariablePage: TPage;
@@ -35,7 +47,6 @@ type
     ComputeBtn: TButton;
     CloseBtn: TButton;
     CompareGroup: TRadioGroup;
-    DistGroup: TRadioGroup;
     VarOneEdit: TEdit;
     VarTwoEdit: TEdit;
     Label2: TLabel;
@@ -49,9 +60,9 @@ type
     procedure CloseBtnClick(Sender: TObject);
     procedure CompareGroupClick(Sender: TObject);
     procedure ComputeBtnClick(Sender: TObject);
-    procedure DistGroupClick(Sender: TObject);
     procedure FormActivate(Sender: TObject);
     procedure FormCreate(Sender: TObject);
+    procedure DistChange(Sender: TObject);
     procedure ResetBtnClick(Sender: TObject);
     procedure Var1InBtnClick(Sender: TObject);
     procedure Var1OutBtnClick(Sender: TObject);
@@ -62,11 +73,22 @@ type
 
   private
     FReportFrame: TReportFrame;
-    FChartFrame: TChartFrame;
+    FCumFreqChartFrame: TChartFrame;
+    FFreqChartFrame: TChartFrame;
     FAutoSized: Boolean;
-    CompareTo: integer;
+    CompareTo: TCompareTo;
-    DistType: integer;
+    CompareDist: TCompareDist;
+    procedure CalcFreq(XValues, FreqValues, CumFreqValues: DblDyneVec;
+      AMin, AMax: Double; ANumIntervals, ANumCases: Integer; DF1: Integer = -1;
+      DF2: Integer = -1);
+    procedure CalcTheoreticalDist(XValues, FreqValues, CumFreqValues: DblDyneVec;
+      ANumIntervals, ANumCases: Integer; out AName: String);
+    procedure Plot(AChartFrame: TChartFrame; Y1Values, Y2Values: DblDyneVec;
+      AName1, AName2: String);
     procedure UpdateBtnStates;
+    procedure UpdateDF1;
+    function Validate(ANumCases: Integer;
+      out AMsg: String; out AControl: TWinControl): Boolean;
 
   public
     procedure Reset; override;
@@ -83,11 +105,125 @@ implementation
 
 uses
   Math,
+  TACustomSeries, TASeries,
   Utils, MathUnit;
 
 
 { TCompareDistFrm }
 
+procedure TCompareDistFrm.CalcFreq(XValues, FreqValues, CumFreqValues: DblDyneVec;
+  AMin, AMax: Double; ANumIntervals, ANumCases: Integer; DF1: Integer = -1;
+  DF2: Integer = -1);
+var
+  dx: Double;
+  i: Integer;
+
+  procedure Calc(AProb1, AProb2: Double);
+  begin
+    FreqValues[i] := abs(AProb2 - AProb1) * ANumCases;
+  end;
+
+begin
+  dx := (AMax - AMin) / ANumIntervals;
+  for i := 0 to ANumIntervals do
+    XValues[i] := AMin + i * dx;
+
+  for i := 0 to ANumIntervals - 1 do
+    case CompareDist of
+      cd_Normal:
+        Calc(NormalDist(XValues[i]), NormalDist(XValues[i+1]));
+      cd_t:
+        Calc(0.5 * ProbT(XValues[i], DF1), 0.5 * ProbT(XValues[i+1], DF1));
+      cd_ChiSq:
+        Calc(ChiSquaredProb(XValues[i], DF1), ChiSquaredProb(XValues[i+1], DF1));
+      cd_F:
+        Calc(ProbF(XValues[i], DF1, DF2), ProbF(XValues[i+1], DF1, DF2));
+      cd_Poisson:
+        Calc(PoissonCDF(round(XValues[i]), DF1), PoissonCDF(round(XValues[i+1]), DF1));
+//        Calc(PoissonPDF(round(XValues[i]), DF1), 0);
+    end;
+
+  CumFreqValues[0] := FreqValues[0];
+  for i := 1 to ANumIntervals - 1 do
+    CumFreqValues[i] := CumFreqValues[i-1] + FreqValues[i];
+end;
+
+
+procedure TCompareDistFrm.CalcTheoreticalDist(XValues, FreqValues, CumFreqValues: DblDyneVec;
+  ANumIntervals, ANumCases: Integer; out AName: String);
+var
+  min, max: Double;
+  DF1: Integer = -1;
+  DF2: Integer = -1;
+  a: Double;
+begin
+  if TryStrToFloat(DF1Edit.Text, a) then
+    DF1 := round(a);
+  if TryStrToFloat(DF2Edit.Text, a) then
+    DF2 := round(a);
+
+  case CompareDist of
+    cd_Normal:
+      begin
+        min := -3.0;
+        max :=  3.0;
+        AName := 'Normal dist';
+      end;
+    cd_t:
+      begin
+        min := -3.0;
+        max :=  3.0;
+        AName := 't dist';
+      end;
+    cd_ChiSq:
+      begin
+        min := 0.0;
+        max := 20.0;
+        AName := 'Chi-sq dist';
+      end;
+    cd_F:
+      begin
+        min := 0.0;
+        max := 2.0;
+        AName := 'F dist';
+      end;
+    cd_Poisson:
+      ; // will be handled separately
+  end;
+
+  CalcFreq(XValues, FreqValues, CumFreqValues, min, max, ANumIntervals, ANumCases, DF1, DF2);
+end;
+
+
+
+(*
+  if NormalDistChk.Checked then // normal distribution curve
+  begin
+    name2 := 'Normal';
+    min2 := -3.0;
+    max2 := 3.0;
+    range2 := max2 - min2;
+    incrsize2 := range2 / noints;
+    Xvalue2[0] := min2;
+    Xvalue2[noints] := max2;
+    for i := 1 to noInts do
+    begin
+      Xvalue2[i-1] := min2 + (i-1) * incrSize2;
+      Xvalue2[i] := min2 + (i) * incrSize2;
+      prob1 := probz(abs(Xvalue2[i-1]));
+      prob2 := probz(abs(Xvalue2[i]));
+      if prob1 > prob2 then
+        Var2Freq[i-1] := round((prob1 - prob2) * nCases)
+      else
+        Var2Freq[i-1] := round((prob2 - prob1) * nCases)
+    end;
+    Cumfreq2[0] := Var2Freq[0];
+    for i := 1 to noints do
+      Cumfreq2[i] := Cumfreq2[i-1] + Var2Freq[i];
+  end
+end;
+*)
+
 procedure TCompareDistFrm.CloseBtnClick(Sender: TObject);
 begin
   Close;
@@ -96,58 +232,52 @@ end;
 
 procedure TCompareDistFrm.CompareGroupClick(Sender: TObject);
 begin
-  compareTo := CompareGroup.ItemIndex;
+  CompareTo := TCompareTo(CompareGroup.ItemIndex);
   Notebook.PageIndex := CompareGroup.ItemIndex;
-  {
-  Label3.Enabled := (compareTo = 1);
-  VarTwoEdit.Enabled := (compareTo = 1);
-  Var2InBtn.Enabled := (compareTo = 1);
-  Var2OutBtn.Enabled := (compareTo = 1);
-  }
 end;
 
 
 procedure TCompareDistFrm.ComputeBtnClick(Sender: TObject);
 var
-  Var1Freq : IntDyneVec = nil;
+  var1Freq: DblDyneVec = nil;  // could be IntDyneVec, but simpler charting this way
-  Var2Freq : IntDyneVec = nil;
+  var2Freq: DblDyneVec = nil;
-  XValue1 : DblDyneVec = nil;
+  xValue1: DblDyneVec = nil;
-  XValue2 : DblDyneVec = nil;
+  xValue2: DblDyneVec = nil;
-  Cumfreq1 : DblDyneVec = nil;
+  cumfreq1: DblDyneVec = nil;
-  Cumfreq2 : DblDyneVec = nil;
+  cumfreq2: DblDyneVec = nil;
-  i, j, k, col1, col2, Ncases, noints : integer;
+  i, j, k, col1, col2, nCases, noInts: integer;
-  min1, max1, min2, max2, range1, range2, value : double;
+  min1, max1, min2, max2, range1, range2, value: double;
-  incrsize1, incrsize2, prob1,prob2, {%H-}KS, mean, DegFree : double;
+  incrSize1, incrSize2, {%H-}KS: double;
-  cellval, name1, name2 : string;
+  cellVal, name1, name2: string;
-  df1, df2 : integer;
-  xtitle : string;
   msg: String;
+  C: TWinControl;
   lReport: TStrings;
 begin
-  SetLength(Var1Freq, NoCases + 1);
+  SetLength(var1Freq, NoCases + 1);
-  SetLength(Var2Freq, NoCases + 1);
+  SetLength(var2Freq, NoCases + 1);
-  SetLength(XValue1,  NoCases + 1);
+  SetLength(xValue1,  NoCases + 1);
-  SetLength(XValue2,  NoCases + 1);
+  SetLength(xValue2,  NoCases + 1);
-  SetLength(Cumfreq1, NoCases + 1);
+  SetLength(cumfreq1, NoCases + 1);
-  SetLength(Cumfreq2, NoCases + 1);
+  SetLength(cumfreq2, NoCases + 1);
 
   // Get columns of the variables
   col1 := 0;
-  col2 := 0;
   for i := 1 to NoVariables do
-  begin
+    if VarOneEdit.Text = OS3MainFrm.DataGrid.Cells[i, 0] then col1 := i;
-    if VarOneEdit.Text = OS3MainFrm.DataGrid.Cells[i,0] then col1 := i;
-    if compareto = 1 then
-    begin
-      if VarTwoEdit.Text = OS3MainFrm.DataGrid.Cells[i,0] then col2 := i;
-    end;
-  end;
 
+  col2 := 0;
+  if CompareTo = ctVariable then
+    for i := 1 to NoVariables do
+      if VarTwoEdit.Text = OS3MainFrm.DataGrid.Cells[i, 0] then col2 := i;
+
+  // Check existence of required variables
   msg := '';
   case CompareTo of
-    0: if col1 = 0 then
+    ctTheoreticalDistrib:
+      if col1 = 0 then
        msg := 'Variable not specified.';
-    1: if col1 = 0 then
+    ctVariable:
+      if col1 = 0 then
         msg := 'Variable One is not specified.'
       else if col2 = 0 then
         msg := 'Variable Two is not specified.';
@@ -158,88 +288,110 @@ begin
     exit;
   end;
 
-  // get min and max values for variable in col1
+  // Get min and max values for variable in col1, as well as true number of cases
-  min1 := 1.0e308;
+  min1 := Infinity;
-  max1 := -1.0e308;
+  max1 := -Infinity;
-  Ncases := 0;
+  nCases := 0;
   for j := 1 to NoCases do
   begin
-    if not ValidValue(j,col1) then continue;
+    if not ValidValue(j, col1) then continue;
-    value := StrToFloat(OS3MainFrm.DataGrid.Cells[col1,j]);
+    value := StrToFloat(OS3MainFrm.DataGrid.Cells[col1, j]);
     if value > max1 then max1 := value;
     if value < min1 then min1 := value;
-    inc(Ncases);
+    inc(nCases);
   end;
 
-  noints := NoCases - 1;   // number of intervals
+  // Validate
-  if noints > 20 then noints := 20;
+  if not Validate(nCases, msg, C) then begin
+    C.SetFocus;
+    ErrorMsg(msg);
+  end;
+
+  // Get number of intervals
+  noInts := NoCases - 1;      // wp: why NoCases here, and not nCases?
+  if noInts > 20 then noints := 20;
+
   range1 := max1 - min1 + 1.0;
-  incrsize1 := range1 / noints;
+  incrSize1 := range1 / noInts;
   name1 := VarOneEdit.Text;
 
-  if compareTo = 1 then
+  // Repeat for variable 2 (if Compare To is selected as "Another variable")
+  if CompareTo = ctVariable then
   begin
-    min2 := 1.0e32;
+    min2 := Infinity;
-    max2 := -1.0e32;
+    max2 := -Infinity;
     for j := 1 to NoCases do
     begin
-      if Not ValidValue(j,col2) then continue;
+      if not ValidValue(j, col2) then continue;
-      value := StrToFloat(OS3MainFrm.DataGrid.Cells[col2,j]);
+      value := StrToFloat(OS3MainFrm.DataGrid.Cells[col2, j]);
       if value > max2 then max2 := value;
       if value < min2 then min2 := value;
     end;
     range2 := max2 - min2 + 1.0;
-    incrsize2 := range2 / noints;
+    incrSize2 := range2 / noInts;
     name2 := VarTwoEdit.Text;
   end;
 
-  //Now, get frequency of cases in each interval
+  // Get frequency of cases in each interval
   for j := 1 to noints+1 do
-    Var1Freq[j-1] := 0;
+    var1Freq[j-1] := 0;
+
   for j := 1 to NoCases do
   begin
-    if Not ValidValue(j,col1) then continue;
+    if not ValidValue(j, col1) then continue;
-    value := StrToFloat(OS3MainFrm.DataGrid.Cells[col1,j]);
+    value := StrToFloat(OS3MainFrm.DataGrid.Cells[col1, j]);
-    for k := 1 to noints do
+    for k := 1 to noInts do
     begin
-      if (value >= min1 + ((k-1) * incrsize1)) and
+      if (value >= min1 + (k-1) * incrSize1) and (value < min1 + k * incrSize1) then
-         (value < min1 + (k * incrsize1))
+        var1Freq[k-1] := var1Freq[k-1] + 1;
-      then
-        Var1Freq[k-1] := Var1Freq[k-1] + 1;
     end;
   end;
-  Cumfreq1[0] := Var1Freq[0];
-  for j := 1 to noints+1 do
-    XValue1[j-1] := min1 + (j-1) * incrsize1;
-  for j := 1 to noints do
-    Cumfreq1[j] := Cumfreq1[j-1] + Var1Freq[j];
-  if compareTo = 1 then // do same for second variable
-  begin
-    for j := 1 to noints+1 do
-      Var2Freq[j-1] := 0;
-    for j := 1 to NoCases do
-    begin
-      if Not ValidValue(j,col2) then continue;
-      value := StrToFloat(OS3MainFrm.DataGrid.Cells[col2,j]);
-      for k := 1 to noints do
-      begin
-        if (value >= min2 + ((k-1) * incrsize2)) and
-           (value < min2 + (k * incrsize2))
-        then
-          Var2Freq[k-1] := Var2Freq[k-1] + 1;
-      end;
-    end;
-    Cumfreq2[0] := Var2Freq[0];
-    for j := 1 to noints+1 do
-      XValue2[j-1] := min2 + (j-1) * incrsize2;
-    for j := 1 to noints do
-      Cumfreq2[j] := Cumfreq2[j-1] + Var2Freq[j];
-  end;
 
-  // Get theoretical distribution frequencies for selected dist.
+  cumFreq1[0] := var1Freq[0];
-  if compareTo = 0 then
+  for j := 1 to noInts+1 do
+    xValue1[j-1] := min1 + (j-1) * incrSize1;
+  for j := 1 to noInts do
+    cumFreq1[j] := cumFreq1[j-1] + var1Freq[j];
+
+  // Repeat for 2nd variable, if required
+  if CompareTo = ctVariable then
   begin
-    if DistGroup.ItemIndex = 0 then // normal curve
+    for j := 1 to noInts+1 do
+      var2Freq[j-1] := 0;
+
+    for j := 1 to NoCases do
+    begin
+      if not ValidValue(j, col2) then continue;
+      value := StrToFloat(OS3MainFrm.DataGrid.Cells[col2, j]);
+      for k := 1 to noInts do
+      begin
+        if (value >= min2 + (k-1) * incrsize2) and (value < min2 + k * incrsize2) then
+          var2Freq[k-1] := var2Freq[k-1] + 1;
+      end;
+    end;
+
+    cumfreq2[0] := var2Freq[0];
+    for j := 1 to noInts+1 do
+      xValue2[j-1] := min2 + (j-1) * incrSize2;
+    for j := 1 to noInts do
+      cumFreq2[j] := cumFreq2[j-1] + var2Freq[j];
+  end;
+
+  // Get theoretical distribution frequencies for selected distribution, if required.
+  if CompareDist = cd_Poisson then
+  begin
+    CalcFreq(xValue2, var2Freq, cumFreq2, min1, min2, noInts, nCases, StrToInt(DF1Edit.Text));
+    name2 := 'Poisson';
+  end
+  else
+    CalcTheoreticalDist(xValue2, var2Freq, cumFreq2, noInts, nCases, name2);
+
+  (*
+
+
+  if CompareTo = ctTheoreticalDistrib then
+  begin
+    if NormalDistChk.Checked then // normal distribution curve
     begin
       name2 := 'Normal';
       min2 := -3.0;
@@ -248,76 +400,76 @@ begin
       incrsize2 := range2 / noints;
       Xvalue2[0] := min2;
       Xvalue2[noints] := max2;
-      for i := 1 to noints do
+      for i := 1 to noInts do
       begin
-        Xvalue2[i-1] := min2 + (i-1) * incrsize2;
+        Xvalue2[i-1] := min2 + (i-1) * incrSize2;
-        Xvalue2[i] := min2 + (i) * incrsize2;
+        Xvalue2[i] := min2 + (i) * incrSize2;
         prob1 := probz(abs(Xvalue2[i-1]));
         prob2 := probz(abs(Xvalue2[i]));
         if prob1 > prob2 then
-          Var2Freq[i-1] := round((prob1-prob2) * Ncases)
+          Var2Freq[i-1] := round((prob1 - prob2) * nCases)
         else
-          Var2Freq[i-1] := round((prob2-prob1) * Ncases)
+          Var2Freq[i-1] := round((prob2 - prob1) * nCases)
       end;
       Cumfreq2[0] := Var2Freq[0];
       for i := 1 to noints do
         Cumfreq2[i] := Cumfreq2[i-1] + Var2Freq[i];
     end
     else
-    if DistGroup.ItemIndex = 1 then // t-distribution
+    if tDistChk.Checked then // t-distribution
     begin
       name2 := 't-Dist.';
       min2 := -3.0;
       max2 := 3.0;
-      df1 := Ncases - 1;
+      df1 := nCases - 1;
       range2 := max2 - min2;
       incrsize2 := range2 / noints;
       Xvalue2[0] := min2;
       Xvalue2[noints] := max2;
-      for i := 1 to noints do
+      for i := 1 to noInts do
       begin
-        Xvalue2[i-1] := min2 + (i-1) * incrsize2;
+        Xvalue2[i-1] := min2 + (i-1) * incrSize2;
-        Xvalue2[i] := min2 + (i) * incrsize2;
+        Xvalue2[i] := min2 + (i) * incrSize2;
         prob1 := 0.5 * probt(Xvalue2[i-1],df1);
         prob2 := 0.5 * probt(Xvalue2[i],df1);
         if prob1 > prob2 then
-          Var2Freq[i-1] := round((prob1-prob2) * Ncases)
+          Var2Freq[i-1] := round((prob1-prob2) * nCases)
         else
-          Var2Freq[i-1] := round((prob2-prob1) * Ncases)
+          Var2Freq[i-1] := round((prob2-prob1) * nCases)
       end;
       Cumfreq2[0] := Var2Freq[0];
-      for i := 1 to noints do
+      for i := 1 to noInts do
         Cumfreq2[i] := Cumfreq2[i-1] + Var2Freq[i];
     end
     else
-    if DistGroup.ItemIndex = 2 then // chi squared distribution
+    if ChiSqDistChk.Checked then // chi squared distribution
     begin
       cellval := InputBox('Deg. Freedom 1 Entry','DF 1','');
       df1 := StrToInt(cellval);
-      name2 := 'Chi Sqrd';
+      name2 := 'Chi Sq';
       min2 := 0.0;
       max2 := 20.0;
       range2 := max2 - min2;
-      incrsize2 := range2 / noints;
+      incrSize2 := range2 / noInts;
-      Xvalue2[0] := min2;
+      xValue2[0] := min2;
-      Xvalue2[noints] := max2;
+      xValue2[noInts] := max2;
       for i := 1 to noints do
       begin
-        Xvalue2[i-1] := min2 + (i-1) * incrsize2;
+        Xvalue2[i-1] := min2 + (i-1) * incrSize2;
-        Xvalue2[i] := min2 + (i) * incrsize2;
+        Xvalue2[i] := min2 + (i) * incrSize2;
         prob1 := chisquaredprob(Xvalue2[i-1],df1);
         prob2 := chisquaredprob(Xvalue2[i],df1);
         if prob1 > prob2 then
-          Var2Freq[i-1] := round((prob1-prob2) * Ncases)
+          Var2Freq[i-1] := round((prob1-prob2) * nCases)
         else
-          Var2Freq[i-1] := round((prob2-prob1) * Ncases)
+          Var2Freq[i-1] := round((prob2-prob1) * nCases)
       end;
-      Cumfreq2[0] := Var2Freq[0];
+      cumfreq2[0] := var2Freq[0];
       for i := 1 to noints do
-        Cumfreq2[i] := Cumfreq2[i-1] + Var2Freq[i];
+        cumfreq2[i] := cumfreq2[i-1] + var2Freq[i];
     end
     else
-    if DistGroup.ItemIndex = 3 then // F distribution
+    if FDistChk.Checked then // F distribution
     begin
       // get degrees of freedom
       cellval := InputBox('Deg. Freedom 1 Entry','DF 1','');
@@ -331,23 +483,23 @@ begin
       incrsize2 := range2 / noints;
       Xvalue2[0] := min2;
       Xvalue2[noints] := max2;
-      for i := 1 to noints do
+      for i := 1 to noInts do
       begin
-        Xvalue2[i-1] := min2 + (i-1) * incrsize2;
+        Xvalue2[i-1] := min2 + (i-1) * incrSize2;
-        Xvalue2[i] := min2 + (i) * incrsize2;
+        Xvalue2[i] := min2 + (i) * incrSize2;
         prob1 := ProbF(Xvalue2[i-1],df1,df2);
         prob2 := ProbF(Xvalue2[i],df1,df2);
         if prob1 > prob2 then
-          Var2Freq[i-1] := round((prob1-prob2) * Ncases)
+          Var2Freq[i-1] := round((prob1-prob2) * nCases)
         else
-          Var2Freq[i-1] := round((prob2-prob1) * Ncases)
+          Var2Freq[i-1] := round((prob2-prob1) * nCases)
       end;
-      Cumfreq2[0] := Var2Freq[0];
+      cumfreq2[0] := Var2Freq[0];
-      for i := 1 to noints do
+      for i := 1 to noInts do
-        Cumfreq2[i] := Cumfreq2[i-1] + Var2Freq[i];
+        cumfreq2[i] := cumfreq2[i-1] + var2Freq[i];
     end
     else
-    if DistGroup.ItemIndex = 4 then // Poisson distribution
+    if PoissonDistChk.Checked then // Poisson distribution
     begin
       name2 := 'Poisson';
       mean := 0; // use as parameter a in pdf call
@@ -358,33 +510,34 @@ begin
         ErrorMsg('Value > 13 found. Factorial too large - exiting.');
         exit;
       end;
-      for i := 1 to Ncases do
+      for i := 1 to nCases do
-        mean := mean + StrToFloat(OS3MainFrm.DataGrid.Cells[col1,i]);
+        mean := mean + StrToFloat(OS3MainFrm.DataGrid.Cells[col1, i]);
-      mean := mean / Ncases;
+      mean := mean / nCases;
       cellval := IntToStr(round(mean));
-      cellval := InputBox('Parameter Entry (mean)','DF 1',cellval);
+      cellval := InputBox('Parameter Entry (mean)', 'DF 1', cellval);
       degfree := StrToFloat(cellval);
       range2 := max2 - min2;
-      incrsize2 := range2 / noints;
+      incrsize2 := range2 / noInts;
 //             Xvalue2[0] := min2;
       Xvalue2[noints] := max2;
       for i := 1 to noints do
       begin
-        Xvalue2[i-1] := min2 + (i-1) * incrsize2;
+        Xvalue2[i-1] := min2 + (i-1) * incrSize2;
-        Xvalue2[i] := min2 + (i) * incrsize2;
+        Xvalue2[i] := min2 + (i) * incrSize2;
         poisson_pdf ( round(Xvalue2[i-1]), degfree, prob1 );
 //                  prob1 := (Xvalue2[i-1],df1);
 //                  prob2 := chisquaredprob(Xvalue2[i],df1);
 //                  if prob1 > prob2 then
-       Var2Freq[i-1] := round((prob1) * Ncases);
+       Var2Freq[i-1] := round((prob1) * nCases);
 //                  else Var2Freq[i-1] := round((prob2-prob1) * Ncases)
       end;
-      Cumfreq2[0] := Var2Freq[0];
+      cumfreq2[0] := var2Freq[0];
-      for i := 1 to noints do
+      for i := 1 to noInts do
-        Cumfreq2[i] := Cumfreq2[i-1] + Var2Freq[i];
+        cumfreq2[i] := cumfreq2[i-1] + var2Freq[i];
     end;
   end;
 
+  *)
   lReport := TStringList.Create;
   try
     lReport.Add('DISTRIBUTION COMPARISON by Bill Miller');
@@ -395,12 +548,14 @@ begin
     lReport.Add('%10s   %10s   %10s   %10s   %10s   %10s', [
       'X1 Value', 'Frequency', 'Cum. Freq.', 'X2 Value', 'Frequency', 'Cum. Freq.'
     ]);
+    lReport.Add('----------   ----------   ----------  ----------   ----------   ----------');
     for i := 1 to noints do
-      lReport.Add('%10.3f   %10d   %10.3f   %10.3f   %10d   %10.3f', [
+      lReport.Add('%10.3f   %10.0f   %10.3f   %10.3f   %10.0f   %10.3f', [
         XValue1[i-1], Var1Freq[i-1], Cumfreq1[i-1], XValue2[i-1], Var2Freq[i-1], Cumfreq2[i-1]
       ]);
+    lReport.Add('');
     cellval := 'D';
-    KS := KolmogorovTest(noints, Cumfreq1,noints, Cumfreq2, cellval, lReport);
+    KS := KolmogorovTest(noInts, Cumfreq1, noInts, Cumfreq2, cellVal, lReport);
   // lReport.Add('Kolmogorov-Smirnov statistic := %5.3f', [KS]);
 
     FReportFrame.DisplayReport(lReport);
@@ -409,6 +564,17 @@ begin
   end;
 
   // plot the cdfs
+  Plot(FCumFreqChartFrame, cumFreq1, cumFreq2, VarOneEdit.Text, name2);
+
+  if BothChk.Checked then
+    Plot(FFreqChartFrame, var1Freq, var2Freq, VarOneEdit.Text, name2);
+
+  FreqChartPage.TabVisible := BothChk.Checked;
+
+  (*
+
+
+
   xtitle := 'Red = ' + VarOneEdit.Text + ' Blue = ' + name2;
   cellval := 'Plot of Cumulative Distributions';
   {
@@ -489,6 +655,7 @@ begin
     GraphFrm.Xpoints := nil;
     GraphFrm.Ypoints := nil;
   end;
+    *)
 
   // clean up
   Cumfreq2 := nil;
@@ -500,9 +667,36 @@ begin
 end;
 
 
-procedure TCompareDistFrm.DistGroupClick(Sender: TObject);
+procedure TCompareDistFrm.DistChange(Sender: TObject);
 begin
-  DistType := DistGroup.ItemIndex;
+  DF1Edit.Visible := CompareDist <> cd_Normal;
+  DF1Label.Visible := DF1Edit.Visible;
+  DF1Label.Caption := 'D.F.';
+
+  DF2Edit.Visible := CompareDist = cd_F;
+  DF2Label.Visible := DF2Edit.Visible;
+
+  if NormalDistChk.Checked then
+    CompareDist := cd_Normal
+  else if tDistChk.Checked then
+  begin
+    CompareDist := cd_t;
+    UpdateDF1;
+  end
+  else if ChiSqDistChk.Checked then
+    CompareDist := cd_ChiSq
+  else if FDistChk.Checked then
+  begin
+    CompareDist := cd_F;
+    DF1Label.Caption := 'D.F. 1';
+  end
+  else if PoissonDistChk.Checked then
+  begin
+    CompareDist := cd_Poisson;
+    DF1Label.Caption := 'Mean';
+    UpdateDF1;
+  end else
+    raise Exception.Create('Distribution not supported.');
 end;
 
 
@@ -534,7 +728,7 @@ begin
   if Width < Constraints.MinWidth then Width := 1;
   if Height < Constraints.MinHeight then Height := 1;
 
-  Notebook.AutoSize := false;
+//  Notebook.AutoSize := false;
   Position := poDesigned;
   FAutoSized := true;
 end;
@@ -551,31 +745,81 @@ begin
   FReportFrame.Parent := ReportPage;
   FReportFrame.Align := alClient;
 
-  FChartFrame := TChartFrame.Create(self);
+  FCumFreqChartFrame := TChartFrame.Create(self);
-  FChartFrame.Parent := ChartPage;
+  FCumFreqChartFrame.Parent := CumFreqChartPage;
-  FChartFrame.Align := alClient;
+  FCumFreqChartFrame.Align := alClient;
-  FChartFrame.Chart.BottomAxis.Intervals.MaxLength := 80;
+  FCumFreqChartFrame.Chart.BottomAxis.Intervals.MaxLength := 80;
-  FChartFrame.Chart.BottomAxis.Intervals.MinLength := 30;
+  FCumFreqChartFrame.Chart.BottomAxis.Intervals.MinLength := 30;
+  FCumFreqChartFrame.SetYTitle('Cumulative frequency');
+  FCumFreqChartFrame.SetTitle('Plot of Cumulative Distributions');
+
+  FFreqChartFrame := TChartFrame.Create(self);
+  FFreqChartFrame.Parent := FreqChartPage;
+  FFreqChartFrame.Align := alClient;
+  FFreqChartFrame.Chart.BottomAxis.Intervals.MaxLength := 80;
+  FFreqChartFrame.Chart.BottomAxis.Intervals.MinLength := 30;
+  FFreqChartFrame.SetYTitle('Frequency');
+  FFreqChartFrame.SetTitle('Plot of Distributions');
 
   Reset;
 end;
 
 
+procedure TCompareDistFrm.Plot(AChartFrame: TChartFrame; Y1Values, Y2Values: DblDyneVec;
+  AName1, AName2: String);
+var
+  ser1, ser2: TChartSeries;
+  plotType: TPlotType;
+begin
+  AChartFrame.Clear;
+
+  if BarPlotBtn.Down then
+    plotType := ptBars
+  else
+    plotType := ptLines;
+
+  ser1 := AChartFrame.PlotXY(plotType, nil, Y1Values, nil, nil, AName1, DATA_COLORS[0]);
+  ser2 := AChartFrame.PlotXY(plotType, nil, Y2Values, nil, nil, AName2, DATA_Colors[1]);
+
+  if (ser1 is TBarSeries) then
+  begin
+    with ser1 as TBarSeries do
+    begin
+      BarWidthPercent := 40;
+      BarOffsetPercent := -20;
+    end;
+    with ser2 as TBarSeries do
+    begin
+      BarWidthPercent := 40;
+      BarOffsetPercent := +20;
+    end;
+  end;
+end;
+
+
 procedure TCompareDistFrm.Reset;
 var
   i: integer;
 begin
   VarList.Clear;
+
   VarOneEdit.Text := '';
   VarTwoEdit.Text := '';
+  DF1Edit.Text := '';
+  DF2Edit.Text := '';
+
   for i := 1 to NoVariables do
     VarList.Items.Add(OS3MainFrm.DataGrid.Cells[i,0]);
+
   CompareGroup.ItemIndex := 0;
   CompareGroupClick(nil);
-  DistGroup.ItemIndex := 0;
+  NormalDistChk.Checked := true;
+  DistChange(nil);
 
   FReportFrame.Clear;
-  FChartFrame.Clear;
+  FCumFreqChartFrame.Clear;
+  FFreqChartFrame.Clear;
+  FreqChartPage.TabVisible := false;
 end;
 
 
@@ -593,7 +837,109 @@ begin
   Var2OutBtn.Enabled := VarTwoEdit.Text <> '';
 
   FReportFrame.UpdateBtnStates;
-  FChartFrame.UpdateBtnStates;
+  FCumFreqChartFrame.UpdateBtnStates;
+  FFreqChartFrame.UpdateBtnStates;
+end;
+
+
+procedure TCompareDistFrm.UpdateDF1;
+
+  procedure DFCandidates(AVarName: String; out AMean: Double; out ANumCases: Integer);
+  var
+    col, i: Integer;
+  begin
+    for col := 1 to NoVariables do
+      if AVarName = OS3MainFrm.DataGrid.Cells[col, 0] then
+      begin
+        AMean := 0;
+        ANumCases := 0;
+        for i := 1 to NoCases do
+          if ValidValue(i, col) then
+          begin
+            AMean := AMean + StrToFloat(OS3MainFrm.DataGrid.Cells[col, i]);
+            inc(ANumCases);
+          end;
+        if ANumCases > 1 then
+          AMean := AMean / ANumCases
+        else
+          AMean := NaN;
+        exit;
+      end;
+    AMean := NaN;
+    ANumCases := -1;
+  end;
+
+var
+  m: Double;
+  n: Integer;
+begin
+  if (CompareTo = ctTheoreticalDistrib) then
+  begin
+    DFCandidates(VarOneEdit.Text, m, n);
+    case CompareDist of
+      cd_t :
+        if n > 0 then
+          DF1Edit.Text := IntToStr(n-1);
+      cd_Poisson:
+        if not IsNaN(m) then
+          DF1Edit.Text := FormatFloat('0', m);
+    end;
+  end;
+end;
+
+
+function TCompareDistFrm.Validate(ANumCases: Integer;
+  out AMsg: String; out AControl: TWinControl): Boolean;
+var
+  n: Integer = 0;
+begin
+  Result := false;
+
+  if CompareDist <> cd_Normal then
+  begin
+    if DF1Edit.Text = '' then
+    begin
+      AMsg := 'This control cannot be empty.';
+      AControl := DF1Edit;
+      exit;
+    end;
+    if not TryStrToInt(DF1Edit.Text, n) or (n < 0) then
+    begin
+      AMsg := 'Positive integer value required.';
+      AControl := DF1Edit;
+      exit;
+    end;
+    if (n >= ANumCases) and (CompareDist <> cd_Poisson) then
+    begin
+      AMsg := 'Degrees of freedom cannot be greater than the number of cases.';
+      AControl := DF1Edit;
+      exit;
+    end;
+  end;
+
+  if CompareDist = cd_F then
+  begin
+    if DF2Edit.Text = '' then
+    begin
+      AMsg := 'This control cannot be empty.';
+      AControl := DF2Edit;
+      exit;
+    end;
+    if not TryStrToInt(DF2Edit.Text, n) or (n < 0) then
+    begin
+      AMsg := 'Positive integer value required.';
+      AControl := DF2Edit;
+      exit;
+    end;
+    if n >= ANumCases then
+    begin
+      AMsg := 'Degrees of freedom cannot be greater than the number of cases.';
+      AControl := DF2Edit;
+      exit;
+    end;
+  end;
+
+  Result := true;
 end;
 
 
@@ -613,6 +959,7 @@ begin
       inc(i);
   end;
   UpdateBtnStates;
+  UpdateDF1;
 end;
 
 

applications/lazstats/source/frames/chartframeunit.pas

@@ -69,6 +69,7 @@ uses
 constructor TChartFrame.Create(AOwner: TComponent);
 begin
   inherited;
+  Name := '';
   {$IF LCL_FullVersion >= 2010000}
   ZoomDragTool.LimitToExtent := [zdDown];
   PanDragTool.LimitToExtent := [pdDown];
@@ -174,7 +175,10 @@ begin
         end;
       end;
     ptBars:
+      begin
         Result := TBarSeries.Create(self);
+        TBarSeries(Result).BarBrush.Color := AColor;
+      end;
     ptArea:
       Result := TAreaSeries.Create(self);
     else