unit DIF; {$MODE Delphi} interface uses LCLIntf, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs, StdCtrls, Buttons, OS3MainUnit, GLOBALS, Math, OUTPUTUNIT, MATRIXLIB, DATAPROCS, FUNCTIONSLIB, GRAPHLib, LResources; type DynamicCharArray = array of char; type TDIFfrm = class(TForm) Memo1: TMemo; Label1: TLabel; VarList: TListBox; ItemInBtn: TBitBtn; ItemOutBtn: TBitBtn; AllBtn: TBitBtn; GrpInBtn: TBitBtn; GrpOutBtn: TBitBtn; Label2: TLabel; Label3: TLabel; GroupVarEdit: TEdit; ItemsList: TListBox; Label4: TLabel; Label5: TLabel; RefGrpEdit: TEdit; TrgtGrpEdit: TEdit; ResetBtn: TButton; ComputeBtn: TButton; ReturnBtn: TButton; GroupBox1: TGroupBox; ItemStatsChk: TCheckBox; TestStatsChk: TCheckBox; ItemCorrsChk: TCheckBox; ItemTestChk: TCheckBox; AlphaChk: TCheckBox; LogisticChk: TCheckBox; MHChk: TCheckBox; Label6: TLabel; LevelsEdit: TEdit; Label7: TLabel; LevelNoEdit: TEdit; Label8: TLabel; Label9: TLabel; LowBoundEdit: TEdit; UpBoundEdit: TEdit; LevelScroll: TScrollBar; Label10: TLabel; Label11: TLabel; Label12: TLabel; CurvesChk: TCheckBox; CountsChk: TCheckBox; procedure ResetBtnClick(Sender: TObject); procedure FormShow(Sender: TObject); procedure ReturnBtnClick(Sender: TObject); procedure ComputeBtnClick(Sender: TObject); procedure ItemInBtnClick(Sender: TObject); procedure ItemOutBtnClick(Sender: TObject); procedure AllBtnClick(Sender: TObject); procedure GrpInBtnClick(Sender: TObject); procedure LowBoundEditExit(Sender: TObject); procedure UpBoundEditExit(Sender: TObject); procedure LevelsEditExit(Sender: TObject); procedure LevelScrollScroll(Sender: TObject; ScrollCode: TScrollCode; var ScrollPos: Integer); private { Private declarations } NoItems : integer; nolevels : integer; tmean, tvar, tsd : double; ColNoSelected : IntDyneVec; ColLabels, RowLabels : StrDyneVec; Means, Variances, StdDevs : DblDyneVec; CorMat : DblDyneMat; // correlations among items and total score Data : IntDyneMat; //store item scores and total score Ubounds : IntDyneVec; // upper and lower bounds of score groups Lbounds : IntdyneVec; Code : DynamicCharArray; // blank, A, B or C ETS codes Level10OK : IntdyneMat; // check that each item category >= 10 RMHRight : IntDyneMat; // no. right for items by score group in reference group RMHWrong : IntDyneMat; // no. wrong for items by score group in reference group FMHRight : IntDyneMat; // no. right for items by score group in focus group FMHWrong : IntDyneMat; // no. wrong for items by score group in focus group RScrGrpCnt : IntDyneMat; // total responses for score groups in reference group FScrGrpCnt : IntDyneMat; // total responses for score groups in focus group NT : IntDyneMat; // total right and wrong in each category of each item Alpha : DblDyneVec; AlphaNum : DblDyneVec; AlphaDen : DblDyneVec; MHDiff : DblDyneVec; ExpA : DblDyneMat; VarA : DblDyneMat; SumA : DblDyneVec; SumExpA : DblDyneVec; SumVarA : DblDyneVec; ChiSqr : DblDyneVec; Prob : DblDyneVec; SEMHDDif : DblDyneVec; Aster : StrDyneVec; C : DblDyneVec; CodeRF : DynamicCharArray; Tot : IntDyneVec; procedure AlphaRel(Sender: TObject); procedure ItemCorrs(Sender: TObject); procedure ItemTestCorrs(Sender: TObject); procedure ItemCurves(Sender: TObject); public { Public declarations } end; var DIFfrm: TDIFfrm; implementation procedure TDIFfrm.ResetBtnClick(Sender: TObject); var i : integer; begin VarList.Clear; ItemsList.Clear; GroupVarEdit.Text := ''; ItemInBtn.Visible := true; ItemOutBtn.Visible := false; AllBtn.Visible := true; GrpInBtn.Visible := true; GrpOutBtn.Visible := false; ItemStatsChk.Checked := true; TestStatsChk.Checked := false; ItemCorrsChk.Checked := false; ItemTestChk.Checked := false; MHChk.Checked := true; LogisticChk.Checked := false; RefGrpEdit.Text := ''; TrgtGrpEdit.Text := ''; for i := 1 to NoVariables do VarList.Items.Add(OS3MainFrm.DataGrid.Cells[i,0]); if NoVariables > 0 then LevelScroll.Max := NoVariables; LevelNoEdit.Text := '1'; LowBoundEdit.Text := '0'; UpBoundEdit.Text := '2'; //allocate space on heap SetLength(ColLabels,NoVariables+1); SetLength(RowLabels,NoVariables+1); SetLength(Means,NoVariables); SetLength(Variances,NoVariables); SetLength(StdDevs,NoVariables); SetLength(CorMat,NoVariables,NoVariables); SetLength(Data,NoCases,NoVariables+3); //group, items, total, flag SetLength(Lbounds,NoVariables); SetLength(Ubounds,NoVariables); SetLength(Tot,NoCases); SetLength(ColNoSelected,NoVariables); end; //------------------------------------------------------------------- procedure TDIFfrm.FormShow(Sender: TObject); begin ResetBtnClick(Self); end; //------------------------------------------------------------------- procedure TDIFfrm.ReturnBtnClick(Sender: TObject); begin ColNoSelected := nil; C := nil; SEMHDDif := nil; Aster := nil; Prob := nil; ChiSqr := nil; SumVarA := nil; SumExpA := nil; SumA := nil; VarA := nil; ExpA := nil; CodeRF := nil; MHDiff := nil; AlphaDen := nil; AlphaNum := nil; Alpha := nil; NT := nil; Level10OK := nil; Code := nil; FScrGrpCnt := nil; RScrGrpCnt := nil; FMHWrong := nil; FMHRight := nil; RMHWrong := nil; RMHRight := nil; Tot := nil; Ubounds := nil; Lbounds := nil; Data := nil; CorMat := nil; StdDevs := nil; Variances := nil; Means := nil; RowLabels := nil; ColLabels := nil; DIFfrm.Hide; end; //------------------------------------------------------------------- procedure TDIFfrm.ComputeBtnClick(Sender: TObject); Label LoopStart; var i, j, k : integer; itm : integer; grpvar : integer; subjgrp : integer; value : integer; subjscore : integer; scrgrpsize : integer; lower, upper : integer; sum : integer; cellstring : string; title : string; nsize : array [1..2] of integer; Rtm, Wtm : double; TotPurge : integer; LoopIt : integer; RItem, FItem : integer; begin LoopIt := 0; OutPutFrm.RichEdit.Clear; OutPutFrm.RichEdit.Lines.Add('Mantel-Haenszel DIF Analysis adapted by Bill Miller from'); OutPutFrm.RichEdit.Lines.Add('EZDIF written by Niels G. Waller'); OutPutFrm.RichEdit.Lines.Add(''); NoItems := ItemsList.Items.Count; for k := 1 to 2 do nsize[k] := 0; // get items to analyze and their labels for i := 1 to NoItems do // items to analyze begin for j := 1 to NoVariables do // variables in grid begin cellstring := OS3MainFrm.DataGrid.Cells[j,0]; if cellstring = ItemsList.Items.Strings[i-1] then begin // matched - save info ColNoSelected[i-1] := j; ColLabels[i-1] := cellstring; RowLabels[i-1] := cellstring; end; // end match end; // next j end; // next i ColLabels[NoItems] := 'TOTAL'; RowLabels[NoItems] := 'TOTAL'; // get the variable number of the grouping code grpvar := 0; for i := 1 to NoVariables do begin cellstring := OS3MainFrm.DataGrid.Cells[i,0]; if cellstring = GroupVarEdit.Text then grpvar := i; end; if grpvar = 0 then begin ShowMessage('Error - No group variable found.'); exit; end; // get number of test score levels nolevels := StrToInt(LevelsEdit.Text); // read data (score group and items) for i := 1 to NoCases do begin subjscore := 0; value := round(StrToFloat(Trim(OS3MainFrm.DataGrid.Cells[grpvar,i]))); subjgrp := 0; if value = StrToInt(RefGrpEdit.Text) then subjgrp := 1; // reference grp if value = StrToInt(TrgtGrpEdit.Text) then subjgrp := 2; // target group if subjgrp = 0 then begin ShowMessage('Error - Bad group code for a subject.'); exit; end; Data[i-1,0] := subjgrp; nsize[subjgrp] := nsize[subjgrp] + 1; for j := 1 to NoItems do begin itm := ColNoSelected[j-1]; value := Round(StrToFloat(Trim(OS3MainFrm.DataGrid.Cells[itm,i]))); if value = 1 then subjscore := subjscore + 1; Data[i-1,j] := value; end; Tot[i-1] := subjscore; end; // obtain item means, variances, standard deviations for total subjects for i := 0 to NoItems-1 do begin Means[i] := 0.0; Variances[i] := 0.0; StdDevs[i] := 0.0; for j := 0 to NoCases - 1 do begin Means[i] := Means[i] + Data[j,i+1]; Variances[i] := Variances[i] + (Data[j,i+1] * Data[j,i+1]); end; Variances[i] := (Variances[i] - (Means[i] * Means[i] / NoCases)) / (NoCases - 1); if Variances[i] <= 0 then begin cellstring := format('Item %d has zero variance. Unselect the item.', [i+1]); ShowMessage(cellstring); ResetBtnClick(Self); exit; end; StdDevs[i] := sqrt(Variances[i]); Means[i] := Means[i] / NoCases; end; // obtain total score mean, variance and stddev tmean := 0.0; tvar := 0.0; tsd := 0.0; for i := 0 to NoCases - 1 do begin tmean := tmean + Tot[i]; tvar := tvar + (Tot[i] * Tot[i]); end; tvar := (tvar - (tmean * tmean / NoCases)) / (NoCases - 1); tsd := sqrt(tvar); tmean := tmean / NoCases; // print descriptives if checked if ItemStatsChk.Checked then begin title := 'Total Means'; DynVectorPrint(Means,NoItems,title,ColLabels,NoCases); title := 'Total Variances'; DynVectorPrint(Variances,NoItems,title,ColLabels,NoCases); title := 'Total Standard Deviations'; DynVectorPrint(StdDevs,NoItems,title,ColLabels,NoCases); end; // Show total test score statistics if checked if TestStatsChk.Checked then begin cellstring := format('Total Score: Mean = %10.3f, Variance = %10.3f, Std.Dev. = %10.3f', [tmean, tvar, tsd]); OutPutFrm.RichEdit.Lines.Add(cellstring); OutPutFrm.RichEdit.Lines.Add(''); OutPutFrm.ShowModal; OutPutFrm.RichEdit.Clear; end; cellstring := format('Reference group size = %d, Focus group size = %d', [nsize[1],nsize[2]]); OutPutFrm.RichEdit.Lines.Add(cellstring); OutPutFrm.RichEdit.Lines.Add(''); OutPutFrm.ShowModal; OutPutFrm.RichEdit.Clear; // get Cronbach alpha for total group if checked if AlphaChk.Checked then AlphaRel(Self); // Get item intercorrelations for total group if checked if ItemCorrsChk.Checked then begin ItemCorrs(Self); OutPutFrm.ShowModal; OutPutFrm.RichEdit.Clear; end; // Get item-total score correlations for total group if checked if ItemTestChk.Checked then begin ItemTestCorrs(Self); OutPutFrm.ShowModal; OutPutFrm.RichEdit.Clear; end; // Show upper and lower bounds for score group bins OutPutFrm.RichEdit.Lines.Add('Conditioning Levels'); OutPutFrm.RichEdit.Lines.Add('Lower Upper'); for i := 0 to nolevels-1 do begin cellstring := format('%5d %5d',[Lbounds[i],Ubounds[i]]); OutPutFrm.RichEdit.Lines.Add(cellstring); end; OutPutFrm.RichEdit.Lines.Add(''); OutPutFrm.ShowModal; // check for zero variance in each group for k := 1 to 2 do // group begin for i := 0 to NoItems-1 do // item begin sum := 0; for j := 0 to NoCases-1 do // subject begin if Data[j,0] = k then // group match ? begin sum := sum + Data[j,i+1]; end; end; end; if ((sum = 0) or (sum = NoVariables)) then begin cellstring := format('Item %d in group %d has zero variance.', [i+1,k]); ShowMessage(cellstring); exit; end; end; // Get count of no. right and wrong for each item in each group SetLength(RMHRight,nolevels,NoItems); SetLength(RMHWrong,nolevels,NoItems); SetLength(FMHRight,nolevels,NoItems); SetLength(FMHWrong,nolevels,NoItems); SetLength(RScrGrpCnt,nolevels,NoItems); SetLength(FScrGrpCnt,nolevels,NoItems); SetLength(Code,NoItems); SetLength(Level10OK,nolevels,NoItems); SetLength(NT,nolevels,NoItems); SetLength(Alpha,NoItems); SetLength(AlphaNum,NoItems); SetLength(AlphaDen,NoItems); SetLength(MHDiff,NoItems); SetLength(CodeRF,NoItems); SetLength(ExpA,nolevels,NoItems); SetLength(VarA,nolevels,NoItems); SetLength(SumA,NoItems); SetLength(SumExpA,NoItems); SetLength(SumVarA,NoItems); SetLength(ChiSqr,NoItems); SetLength(Prob,NoItems); SetLength(Aster,NoItems); SetLength(SEMHDDif,NoItems); SetLength(C,NoItems); LoopStart: // clear arrays for j := 0 to NoItems-1 do begin for k := 0 to nolevels-1 do begin RMHRight[k,j] := 0; RMHWrong[k,j] := 0; RScrGrpCnt[k,j] := 0; FMHRight[k,j] := 0; FMHWrong[k,j] := 0; FScrGrpCnt[k,j] := 0; Level10OK[k,j] := 1; NT[k,j] := 0; ExpA[k,j] := 0.0; VarA[k,j] := 0.0; end; Alpha[j] := 0.0; AlphaNum[j] := 0.0; AlphaDen[j] := 0.0; MHDiff[j] := 0.0; CodeRF[j] := ' '; Prob[j] := 0.0; end; LoopIt := LoopIt + 1; OutPutFrm.RichEdit.Clear; cellstring := format('COMPUTING M-H CHI-SQUARE, PASS # %d',[LoopIt]); OutPutFrm.RichEdit.Lines.Add(cellstring); for k := 0 to nolevels-1 do begin for i := 0 to NoCases-1 do begin subjgrp := Data[i,0]; for j := 0 to NoItems-1 do begin RItem := 0; value := Data[i,j+1]; if ((LoopIt = 2) and (Code[j] = 'C')) then RItem := value; if value = 1 then begin if ((Tot[i]+RItem >= Lbounds[k]) and (Tot[i]+RItem <= Ubounds[k])) then begin if subjgrp = 1 then begin RMHRight[k,j] := RMHRight[k,j] + 1; RScrGrpCnt[k,j] := RScrGrpCnt[k,j] + 1; end; // if reference group if subjgrp = 2 then begin FMHRight[k,j] := FMHRight[k,j] + 1; FScrGrpCnt[k,j] := FScrGrpCnt[k,j] + 1; end; // if focus group end; // end if () and () end; // value = 1 if value = 0 then begin if ((Tot[i]+RItem >= Lbounds[k]) and (Tot[i]+RItem <= Ubounds[k])) then begin if subjgrp = 1 then begin RMHWrong[k,j] := RMHWrong[k,j] + 1; RScrGrpCnt[k,j] := RScrGrpCnt[k,j] + 1; end; if subjgrp = 2 then begin FMHWrong[k,j] := FMHWrong[k,j] + 1; FScrGrpCnt[k,j] := FScrGrpCnt[k,j] + 1; end; end; end; // if value = 0 end; // next j end; // next i end; // next k for j := 0 to NoItems-1 do Code[j] := 'Z'; // clean out ETS code // print score group counts for Reference and focus subjects if CountsChk.Checked then begin for i := 0 to nolevels-1 do RowLabels[i] := format('%3d-%3d',[Lbounds[i],Ubounds[i]]); DynIntMatPrint(RScrGrpCnt,nolevels,NoItems,'Score Level Counts by Item',RowLabels,ColLabels, 'Cases in Reference Group'); DynIntMatPrint(FScrGrpCnt,nolevels,NoItems,'Score Level Counts by Item',RowLabels,ColLabels, 'Cases in Focus Group'); end; // Plot Item curves if checked if ((CurvesChk.Checked) and (LoopIt = 1)) then ItemCurves(Self); // check for minimum of 10 per category in each item // compute NT for j := 0 to NoItems-1 do begin for k := 0 to nolevels-1 do begin if ((RScrGrpCnt[k,j] < 10) or (FScrGrpCnt[k,j] < 10)) then Level10OK[k,j] := 0 // insufficient n else Level10OK[k,j] := 1; // 10 or more - OK NT[k,j] := RScrGrpCnt[k,j] + FScrGrpCnt[k,j]; end; end; for k := 0 to nolevels-1 do begin if Level10OK[k,0] = 0 then begin cellstring := format('Insufficient data found in level: %d - %d', [Lbounds[k],Ubounds[k]]); OutPutFrm.RichEdit.Lines.Add(cellstring); end; end; // compute alpha for j := 0 to NoItems - 1 do begin for k := 0 to nolevels-1 do begin if Level10OK[k,j] = 1 then begin AlphaNum[j] := AlphaNum[j] + (RMHRight[k,j] * FMHWrong[k,j]) / NT[k,j]; AlphaDen[j] := AlphaDen[j] + (RMHWrong[k,j] * FMHRight[k,j]) / NT[k,j]; end; end; end; for j := 0 to NoItems-1 do begin if AlphaDen[j] = 0.0 then begin cellstring := format('Window too small at item %d level %d', [j+1,k+1]); ShowMessage(cellstring); exit; end else begin Alpha[j] := AlphaNum[j] / AlphaDen[j]; MHDiff[j] := -2.35 * ln(Alpha[j]); end; end; // compute expected values for j := 0 to NoItems-1 do begin for k := 0 to nolevels-1 do begin if Level10OK[k,j] = 1 then begin ExpA[k,j] := (RScrGrpCnt[k,j] * (RMHRight[k,j] + FMHRight[k,j] )) / NT[k,j]; end; end; end; // compute variances for j := 0 to NoItems-1 do begin for k := 0 to nolevels-1 do begin if Level10OK[k,j] = 1 then begin Rtm := RMHRight[k,j] + FMHRight[k,j]; Wtm := RMHWrong[k,j] + FMHWrong[k,j]; VarA[k,j] := (RScrGrpCnt[k,j] * FScrGrpCnt[k,j] * Rtm * Wtm) / ( NT[k,j] * NT[k,j] * (NT[k,j]-1) ); end; end; end; // compute chi-squares for j := 0 to NoItems-1 do begin SumA[j] := 0.0; SumExpA[j] := 0.0; SumVarA[j] := 0.0; for k := 0 to nolevels-1 do begin if Level10OK[k,j] = 1 then begin SumA[j] := SumA[j] + RMHRight[k,j]; SumExpA[j] := SumExpA[j] + ExpA[k,j]; SumVarA[j] := SumVarA[j] + VarA[k,j]; end; end; end; for j := 0 to NoItems-1 do begin ChiSqr[j] := (sqr((Abs(SumA[j] - SumExpA[j]) - 0.5))) / SumVarA[j]; Prob[j] := 1.0 - chisquaredprob(ChiSqr[j],1); if Prob[j] > 0.05 then Aster[j] := ''; if Prob[j] <= 0.05 then Aster[j] := '*'; if Prob[j] <= 0.01 then Aster[j] := '**'; if Prob[j] <= 0.005 then Aster[j] := '***'; end; // compute std. errors for j := 0 to NoItems-1 do begin C[j] := 0.0; for k := 0 to nolevels-1 do begin if Level10OK[k,j] = 1 then C[j] := C[j] + ((RMHRight[k,j] * FMHWrong[k,j]) / NT[k,j]); end; end; for j := 0 to NoItems - 1 do begin SEMHDDif[j] := 0.0; for k := 0 to nolevels-1 do begin if Level10OK[k,j] = 1 then begin SEMHDDif[j] := SEMHDDif[j] + ( (RMHRight[k,j] * FMHWrong[k,j] ) + ( Alpha[j] * RMHWrong[k,j] * FMHRight[k,j])) * ( RMHRight[k,j] + FMHWrong[k,j] + Alpha[j] * ( RMHWrong[k,j] + FMHRight[k,j] )) / ( 2.0 * NT[k,j] * NT[k,j]); end; end; end; for j := 0 to NoItems-1 do SEMHDDif[j] := (2.35 / C[j]) * sqrt(SEMHDDif[j]); // code results with ETS codes for j := 0 to NoItems-1 do begin if ( (abs(MHDiff[j]) > 1.5) and ((abs(MHDiff[j]) - (1.96 * SEMHDDif[j]) > 1.0))) then Code[j] := 'C'; if ((abs(MHDiff[j]) - (1.96 * SEMHDDif[j]) <= 0.0) or (abs(MHDiff[j]) <= 1.0)) then code[j] := 'A'; if ((code[j] <> 'A') and (code[j] <> 'C')) then code[j] := 'B'; end; // purge TotPurge := 0; for j := 0 to NoItems-1 do begin if (code[j] = 'C') then begin TotPurge := TotPurge + 1; for i := 0 to NoCases - 1 do Tot[i] := Tot[i] - Data[i,j+1]; if Alpha[j] > 1.0 then CodeRF[j] := 'R'; if Alpha[j] < 1.0 then CodeRF[j] := 'F'; end; end; // show results // OutPutFrm.RichEdit.Clear; OutPutFrm.RichEdit.Lines.Add( 'CODES ITEM SIG. ALPHA CHI2 P-VALUE MH D-DIF S.E. MH D-DIF'); for j := 0 to noitems-1 do begin cellstring := format('%1s %1s %4d %3s %6.3f %7.3f %6.3f %6.3f %6.3f', [code[j],CodeRF[j], j+1, Aster[j],Alpha[j],ChiSqr[j],Prob[j],MHDiff[j], SEMHDDif[j]]); OutPutFrm.RichEdit.Lines.Add(cellstring); end; OutPutFrm.RichEdit.Lines.Add(''); if LoopIt = 1 then begin cellstring := format('No. of items purged in pass 1 = %d',[TotPurge]); OutPutFrm.RichEdit.Lines.Add(cellstring); OutPutFrm.RichEdit.Lines.Add('Item Numbers:'); for j := 0 to NoItems-1 do begin if Code[j] = 'C' then begin cellstring := format('%d',[j+1]); OutPutFrm.RichEdit.Lines.Add(cellstring); end; end; end; OutPutFrm.RichEdit.Lines.Add(''); OutPutFrm.ShowModal; if LoopIt < 2 then goto LoopStart; end; //------------------------------------------------------------------- procedure TDIFfrm.ItemInBtnClick(Sender: TObject); var index, i : integer; begin if VarList.ItemIndex < 0 then begin ItemInBtn.Visible := false; exit; end; index := VarList.Items.Count; i := 0; while i < index do begin if (VarList.Selected[i]) then begin ItemsList.Items.Add(VarList.Items.Strings[i]); VarList.Items.Delete(i); index := index - 1; i := 0; end else i := i + 1; end; ItemOutBtn.Visible := true; end; //------------------------------------------------------------------- procedure TDIFfrm.ItemOutBtnClick(Sender: TObject); var index: integer; begin index := ItemsList.ItemIndex; if index < 0 then begin ItemOutBtn.Visible := false; exit; end; VarList.Items.Add(ItemsList.Items.Strings[index]); ItemsList.Items.Delete(index); ItemInBtn.Visible := true; end; //------------------------------------------------------------------- procedure TDIFfrm.AllBtnClick(Sender: TObject); var i : integer; begin if VarList.Items.Count < 1 then exit; for i := 0 to VarList.Items.Count - 1 do ItemsList.Items.Add(VarList.Items.Strings[i]); VarList.Clear; ItemInBtn.Visible := false; ItemOutBtn.Visible := true; end; //------------------------------------------------------------------- procedure TDIFfrm.GrpInBtnClick(Sender: TObject); var index : integer; begin if VarList.ItemIndex < 0 then begin GrpInBtn.Visible := false; exit; end; index := VarList.ItemIndex; GroupVarEdit.Text := VarList.Items.Strings[index]; VarList.Items.Delete(index); GrpInBtn.Visible := false; GrpOutBtn.Visible := true; end; //------------------------------------------------------------------- procedure TDIFfrm.LowBoundEditExit(Sender: TObject); var i : integer; begin i := StrToInt(LevelNoEdit.Text); Lbounds[i-1] := StrToInt(LowBoundEdit.Text); UpBoundEdit.SetFocus; end; //------------------------------------------------------------------- procedure TDIFfrm.UpBoundEditExit(Sender: TObject); var i : integer; begin i := StrToInt(LevelNoEdit.Text); Ubounds[i-1] := StrToInt(UpBoundEdit.Text); if i = StrToInt(LevelsEdit.Text) then begin ComputeBtn.SetFocus; exit; end; LowBoundEdit.Text := IntToStr(Ubounds[i-1] + 1); LowBoundEdit.SetFocus; end; //------------------------------------------------------------------- procedure TDIFfrm.LevelsEditExit(Sender: TObject); begin LevelScroll.Max := StrToInt(LevelsEdit.Text); LowBoundEdit.SetFocus; end; //------------------------------------------------------------------- procedure TDIFfrm.LevelScrollScroll(Sender: TObject; ScrollCode: TScrollCode; var ScrollPos: Integer); var scrlpos : integer; level : integer; begin level := StrToInt(LevelNoEdit.Text); scrlpos := LevelScroll.Position; if ((scrlpos > level) and (level <= StrToInt(LevelsEdit.Text))) then begin LevelNoEdit.Text := IntToStr(scrlpos); LowBoundEdit.SetFocus; exit; end; if scrlpos < level then begin level := scrlpos; if level > 0 then begin LevelNoEdit.Text := IntToStr(level); LowBoundEdit.Text := IntToStr(Lbounds[level-1]); UpBoundEdit.Text := IntToStr(Ubounds[level-1]); end; LowBoundEdit.SetFocus; end; end; //------------------------------------------------------------------- procedure TDIFfrm.AlphaRel(Sender: TObject); var i : integer; AlphaRel, SEMeas : double; outline : string; begin OutPutFrm.RichEdit.Clear; OutPutFrm.RichEdit.Lines.Add(''); AlphaRel := 0.0; for i := 0 to NoItems-1 do AlphaRel := AlphaRel + variances[i]; // sum of item variances AlphaRel := AlphaRel / tvar; AlphaRel := 1.0 - AlphaRel; AlphaRel := (NoItems / (NoItems - 1.0)) * AlphaRel; SEMeas := tsd * sqrt(1.0 - AlphaRel); outline := format('Alpha Reliability Estimate for Test = %6.4f S.E. of Measurement = %8.3f', [AlphaRel,SEMeas]); OutPutFrm.RichEdit.Lines.Add(outline); // OutPutFrm.ShowModal; end; //------------------------------------------------------------------- procedure TDIFfrm.ItemCorrs(Sender: TObject); var i, j, k : integer; title : string; begin // cross-products for i := 0 to NoItems-1 do for j := 0 to NoItems-1 do for k := 0 to NoCases-1 do CorMat[i,j] := CorMat[i,j] + (Data[k,i+1] * Data[k,j+1]); // covariances for i := 0 to NoItems-1 do for j := 0 to NoItems-1 do CorMat[i,j] := (CorMat[i,j] - (NoCases * Means[i] * Means[j])) / (NoCases-1); // correlations for i := 0 to NoItems-1 do for j := 0 to NoItems-1 do CorMat[i,j] := CorMat[i,j] / (StdDevs[i] * StdDevs[j]); // show results OutPutFrm.RichEdit.Clear; title := 'Correlations Among Items'; MAT_PRINT(CorMat,NoItems,NoItems,title,RowLabels,ColLabels,NoCases); end; //------------------------------------------------------------------- procedure TDIFfrm.ItemTestCorrs(Sender: TObject); var i, j : integer; Cors : DblDyneVec; title : string; begin SetLength(Cors,NoItems); // cross-products for i := 0 to NoItems-1 do for j := 0 to NoCases-1 do Cors[i] := Cors[i] + (Data[j,i+1] * Tot[j]); // covariances for i := 0 to NoItems-1 do Cors[i] := (Cors[i] - (NoCases * Means[i] * tmean)) / (NoCases-1); // correlations for i := 0 to NoItems-1 do Cors[i] := Cors[i] / (StdDevs[i] * tsd); // show results // OutPutFrm.RichEdit.Clear; title := 'Item-Total Correlations'; DynVectorPrint(Cors,NoItems,title,ColLabels,NoCases); // release memory Cors := nil; end; //------------------------------------------------------------------- procedure TDIFfrm.ItemCurves(Sender: TObject); var i, ii, j : integer; XPlotPts : DblDyneMat; YPlotPts : DblDyneMat; LabelStr, outline, xTitle, yTitle : string; max : integer; begin SetLength(YPlotPts,2,nolevels); SetLength(XPlotPts,1,nolevels); // get maximum no. of scores in either groups bins for i := 0 to NoItems-1 do begin max := 0; for j := 0 to nolevels-1 do begin if RMHRight[j,i] > max then max := RMHRight[j,i]; if FMHRight[j,i] > max then max := FMHRight[j,i]; end; // Plot reference group in blue, focus group in red for ii := 1 to 2 do // possible group curves begin for j := 0 to nolevels-1 do //get points to plot begin XPlotPts[0,j] := Lbounds[j]; if ii = 1 then YPlotPts[ii-1,j] := RMHRight[j,i]; if ii = 2 then YPlotPts[ii-1,j] := FMHRight[j,i]; end; end; // next group // Plot the points GraphFrm.BackColor := clWhite; GraphFrm.ShowLeftWall := true; GraphFrm.ShowRightWall := true; GraphFrm.ShowBottomWall := true; GraphFrm.ShowBackWall := true; GraphFrm.BackColor := clYellow; GraphFrm.WallColor := clBlue; GraphFrm.FloorColor := clBlue; outline := format('Blue = Reference, Red = Focus for item %d',[i+1]); GraphFrm.Heading := outline; xTitle := 'Lower bounds of levels'; GraphFrm.XTitle := xTitle; yTitle := 'Frequencies'; GraphFrm.YTitle := yTitle; GraphFrm.nosets := 2; GraphFrm.nbars := nolevels; GraphFrm.barwideprop := 0.5; GraphFrm.miny := 0.0; GraphFrm.maxy := max; GraphFrm.AutoScale := false; GraphFrm.GraphType := 5; // 2d line charts GraphFrm.PtLabels := false; for ii := 1 to 2 do begin if ii = 1 then LabelStr := 'Reference'; if ii = 2 then LabelStr := 'Focus'; GraphFrm.SetLabels[ii] := LabelStr; end; GraphFrm.Ypoints := YPlotPts; GraphFrm.Xpoints := XPlotPts; GraphFrm.ShowModal; end; // next item XPlotPts := nil; YPlotPts := nil; end; //------------------------------------------------------------------- initialization {$i DIF.lrs} {$i DIF.lrs} end.