diff --git a/applications/lazstats/LazStats.chm b/applications/lazstats/LazStats.chm
index 1c3c7a5ab..994237613 100644
Binary files a/applications/lazstats/LazStats.chm and b/applications/lazstats/LazStats.chm differ
diff --git a/applications/lazstats/docs/HelpNDoc/LazStats.hnd b/applications/lazstats/docs/HelpNDoc/LazStats.hnd
index 029f689ac..1c653a444 100644
Binary files a/applications/lazstats/docs/HelpNDoc/LazStats.hnd and b/applications/lazstats/docs/HelpNDoc/LazStats.hnd differ
diff --git a/applications/lazstats/source/LazStats.lpi b/applications/lazstats/source/LazStats.lpi
index 8b7238010..b1579110d 100644
--- a/applications/lazstats/source/LazStats.lpi
+++ b/applications/lazstats/source/LazStats.lpi
@@ -297,7 +297,7 @@
       <Unit23>
         <Filename Value="forms\analysis\descriptive\multxvsyunit.pas"/>
         <IsPartOfProject Value="True"/>
-        <ComponentName Value="MultXvsYFrm"/>
+        <ComponentName Value="MultXvsYForm"/>
         <HasResources Value="True"/>
         <ResourceBaseClass Value="Form"/>
         <UnitName Value="MultXvsYUnit"/>
diff --git a/applications/lazstats/source/forms/analysis/descriptive/multxvsyunit.lfm b/applications/lazstats/source/forms/analysis/descriptive/multxvsyunit.lfm
index b698cd28f..0f49e2757 100644
--- a/applications/lazstats/source/forms/analysis/descriptive/multxvsyunit.lfm
+++ b/applications/lazstats/source/forms/analysis/descriptive/multxvsyunit.lfm
@@ -1,27 +1,38 @@
-inherited MultXvsYFrm: TMultXvsYFrm
+inherited MultXvsYForm: TMultXvsYForm
+  Height = 382
   HelpType = htKeyword
   HelpKeyword = 'html/MultipleGroupXVersusYPlot.htm'
   Caption = 'Multiple X Versus Y Plot'
+  ClientHeight = 382
   inherited ParamsPanel: TPanel
+    Height = 366
     Width = 344
+    ClientHeight = 366
     ClientWidth = 344
     inherited CloseBtn: TButton
       Left = 289
+      Top = 341
       TabOrder = 15
     end
     inherited ComputeBtn: TButton
       Left = 205
+      Top = 341
       TabOrder = 14
     end
     inherited ResetBtn: TButton
       Left = 143
+      Top = 341
       TabOrder = 13
     end
     inherited HelpBtn: TButton
       Left = 84
+      Top = 341
+      HelpType = htKeyword
+      HelpKeyword = 'html/MultipleGroupXVersusYPlot.htm'
       TabOrder = 12
     end
     inherited ButtonBevel: TBevel
+      Top = 325
       Width = 344
     end
     object Label5: TLabel[5]
@@ -30,7 +41,7 @@ inherited MultXvsYFrm: TMultXvsYFrm
       AnchorSideTop.Side = asrCenter
       Left = 0
       Height = 15
-      Top = 374
+      Top = 306
       Width = 46
       Caption = 'Plot Title'
       ParentColor = False
@@ -42,7 +53,7 @@ inherited MultXvsYFrm: TMultXvsYFrm
       AnchorSideBottom.Control = ButtonBevel
       Left = 54
       Height = 23
-      Top = 370
+      Top = 302
       Width = 290
       Anchors = [akLeft, akRight, akBottom]
       BorderSpacing.Left = 8
@@ -63,9 +74,10 @@ inherited MultXvsYFrm: TMultXvsYFrm
       AnchorSideTop.Control = Label1
       AnchorSideTop.Side = asrBottom
       AnchorSideRight.Control = XInBtn
+      AnchorSideBottom.Control = OptionsGroup
       AnchorSideBottom.Side = asrBottom
       Left = 0
-      Height = 309
+      Height = 277
       Top = 17
       Width = 153
       Anchors = [akTop, akLeft, akRight, akBottom]
@@ -178,7 +190,7 @@ inherited MultXvsYFrm: TMultXvsYFrm
       AnchorSideBottom.Control = LabelEdit
       Left = 159
       Height = 49
-      Top = 313
+      Top = 245
       Width = 182
       Anchors = [akLeft, akBottom]
       AutoSize = True
@@ -295,9 +307,11 @@ inherited MultXvsYFrm: TMultXvsYFrm
   end
   inherited ParamsSplitter: TSplitter
     Left = 356
+    Height = 382
   end
   inherited PageControl: TPageControl
     Left = 365
+    Height = 366
     Width = 343
   end
 end
diff --git a/applications/lazstats/source/forms/analysis/descriptive/multxvsyunit.pas b/applications/lazstats/source/forms/analysis/descriptive/multxvsyunit.pas
index 811c3c450..0980ad83f 100644
--- a/applications/lazstats/source/forms/analysis/descriptive/multxvsyunit.pas
+++ b/applications/lazstats/source/forms/analysis/descriptive/multxvsyunit.pas
@@ -14,9 +14,9 @@ uses
 
 type
 
-  { TMultXvsYFrm }
+  { TMultXvsYForm }
 
-  TMultXvsYFrm = class(TBasicStatsReportAndChartForm)
+  TMultXvsYForm = class(TBasicStatsReportAndChartForm)
     XInBtn: TBitBtn;
     XOutBtn: TBitBtn;
     YInBtn: TBitBtn;
@@ -59,7 +59,7 @@ type
   end; 
 
 var
-  MultXvsYFrm: TMultXvsYFrm;
+  MultXvsYForm: TMultXvsYForm;
 
 implementation
 
@@ -67,18 +67,18 @@ implementation
 
 uses
   TATypes,
-  Math, Utils, MatrixUnit;
+  Math, Utils, MatrixUnit, GridProcs;
 
 
-{ TMultXvsYFrm }
+{ TMultXvsYForm }
 
-constructor TMultXvsYFrm.Create(AOwner: TComponent);
+constructor TMultXvsYForm.Create(AOwner: TComponent);
 begin
   inherited;
 end;
 
 
-procedure TMultXvsYFrm.AdjustConstraints;
+procedure TMultXvsYForm.AdjustConstraints;
 begin
   ParamsPanel.Constraints.MinWidth := Max(
     4*CloseBtn.Width + 3*CloseBtn.BorderSpacing.Left,
@@ -89,11 +89,10 @@ begin
 end;
 
 
-procedure TMultXvsYFrm.Compute;
+procedure TMultXvsYForm.Compute;
 var
   i, N, xCol, yCol, grpCol, grp, numGrps: integer;
   grpName: String;
-  //minX, maxX, minY, maxY,
   X, Y: double;
   cellstring: string;
   numInGrp: IntDyneVec = nil;
@@ -109,17 +108,10 @@ begin
   SetLength(stdDevs, 2);
 
   // Get selected variables
-  xCol := 0;
-  yCol := 0;
-  grpCol := 0;
-  for i := 1 to NoVariables do
-  begin
-    cellstring  :=  OS3MainFrm.DataGrid.Cells[i, 0];
-    if (cellstring = XEdit.Text) then xCol := i;
-    if (cellstring = YEdit.Text) then yCol := i;
-    if (cellstring = GroupEdit.Text) then grpCol := i;
-  end;
-  if (xCol = 0) or (yCol = 0) or (grpCol = 0) then
+  xCol := GetVariableIndex(OS3MainFrm.DataGrid, XEdit.Text);
+  yCol := GetVariableIndex(OS3MainFrm.DataGrid, YEdit.Text);
+  grpCol := GetVariableIndex(OS3MainFrm.DataGrid, GroupEdit.Text);
+  if (xCol = -1) or (yCol = -1) or (grpCol = -1) then
   begin
     ErrorMsg('No variable selected.');
     exit;
@@ -152,7 +144,7 @@ begin
   N := 0;
   for i := 1 to NoCases do
   begin
-    if not GoodRecord(i, Length(selected), selected) then continue;
+    if not GoodRecord(OS3MainFrm.Datagrid, i, selected) then continue;
     inc(N);
 
     X := StrToFloat(OS3MainFrm.DataGrid.Cells[XCol, i]);
@@ -199,7 +191,7 @@ begin
 end;
 
 
-procedure TMultXvsYFrm.GroupInBtnClick(Sender: TObject);
+procedure TMultXvsYForm.GroupInBtnClick(Sender: TObject);
 var
   i: integer;
 begin
@@ -213,7 +205,7 @@ begin
 end;
 
 
-procedure TMultXvsYFrm.GroupOutBtnClick(Sender: TObject);
+procedure TMultXvsYForm.GroupOutBtnClick(Sender: TObject);
 begin
   if GroupEdit.Text <> '' then
   begin
@@ -227,7 +219,7 @@ end;
 // Routine to plot X versus multiple Y values for several groups
 // Layout of X and Y matrices:
 //   1st index: group index, 2nd index: point index within group
-procedure TMultXvsYFrm.PlotXY(const XValues, YValues: DblDyneMat;
+procedure TMultXvsYForm.PlotXY(const XValues, YValues: DblDyneMat;
   const Groups: StrDyneVec);
 var
   pt: TPlotType;
@@ -255,25 +247,20 @@ begin
 end;
 
 
-procedure TMultXvsYFrm.Reset;
-var
-  i: integer;
+procedure TMultXvsYForm.Reset;
 begin
   inherited;
 
-  VarList.Clear;
-  for i := 1 to NoVariables do
-    VarList.Items.Add(OS3MainFrm.DataGrid.Cells[i,0]);
+  CollectVariableNames(OS3MainFrm.DataGrid, varList.Items);
   XEdit.Text := '';
   YEdit.Text := '';
   GroupEdit.Text := '';
-  LinesChk.Checked := false;
 	
   UpdateBtnStates;
 end;
 
 
-procedure TMultXvsYFrm.VarListDblClick(Sender: TObject);
+procedure TMultXvsYForm.VarListDblClick(Sender: TObject);
 var
   index: Integer;
 begin
@@ -292,7 +279,7 @@ begin
 end;
 
 
-procedure TMultXvsYFrm.UpdateBtnStates;
+procedure TMultXvsYForm.UpdateBtnStates;
 var
   lSelected: Boolean;
   i: Integer;
@@ -316,13 +303,13 @@ begin
 end;
 
 
-procedure TMultXvsYFrm.VarListSelectionChange(Sender: TObject; User: boolean);
+procedure TMultXvsYForm.VarListSelectionChange(Sender: TObject; User: boolean);
 begin
   UpdateBtnStates;
 end;
 
 
-procedure TMultXVsYFrm.WriteToReport(const AMeans, AStdDevs: DblDyneVec);
+procedure TMultXvsYForm.WriteToReport(const AMeans, AStdDevs: DblDyneVec);
 var
   lReport: TStrings;
 begin
@@ -348,7 +335,7 @@ begin
 end;
 
 
-procedure TMultXvsYFrm.XInBtnClick(Sender: TObject);
+procedure TMultXvsYForm.XInBtnClick(Sender: TObject);
 var
   i: integer;
 begin
@@ -362,7 +349,7 @@ begin
 end;
 
 
-procedure TMultXvsYFrm.XOutBtnClick(Sender: TObject);
+procedure TMultXvsYForm.XOutBtnClick(Sender: TObject);
 begin
   if XEdit.Text <> '' then
   begin
@@ -373,7 +360,7 @@ begin
 end;
 
 
-procedure TMultXvsYFrm.YInBtnClick(Sender: TObject);
+procedure TMultXvsYForm.YInBtnClick(Sender: TObject);
 var
   i: integer;
 begin
@@ -387,7 +374,7 @@ begin
 end;
 
 
-procedure TMultXvsYFrm.YOutBtnClick(Sender: TObject);
+procedure TMultXvsYForm.YOutBtnClick(Sender: TObject);
 begin
   if YEdit.Text <> '' then
   begin
diff --git a/applications/lazstats/source/forms/mainunit.pas b/applications/lazstats/source/forms/mainunit.pas
index b916c6687..9359565ed 100644
--- a/applications/lazstats/source/forms/mainunit.pas
+++ b/applications/lazstats/source/forms/mainunit.pas
@@ -1998,9 +1998,9 @@ end;
 //Menu "Analysis" > "Descriptive" > "Multiple Group X vs Y Plot"
 procedure TOS3MainFrm.mnuAnalysisDescr_MultXvsYClick(Sender: TObject);
 begin
-  if MultXvsYFrm = nil then
-    Application.CreateForm(TMultXvsYFrm, MultXvsYFrm);
-  MultXvsYFrm.Show;
+  if MultXvsYForm = nil then
+    Application.CreateForm(TMultXvsYForm, MultXvsYForm);
+  MultXvsYForm.Show;
 end;
 
 // Menu "Analysis" > "Descriptive" > "Normality Tests"
diff --git a/applications/lazstats/source/units/mathunit.pas b/applications/lazstats/source/units/mathunit.pas
index 47f84d97e..6abdc1a60 100644
--- a/applications/lazstats/source/units/mathunit.pas
+++ b/applications/lazstats/source/units/mathunit.pas
@@ -158,7 +158,8 @@ end;
   Probability = 0 ... 1 --> Result = -INF ... +INF
 
   Algorithm by Peter John Acklam.
-  http://home.online.no/~pjacklam/notes/invnorm/index.html     }
+  http://home.online.no/~pjacklam/notes/invnorm/index.html  --- no longer valid!
+  https://stackedboxes.org/2017/05/01/acklams-normal-quantile-function/ }
 function InverseNormalDist(Probability: Double): Double;
 const
   A: array[1..6] of Double = (