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Table 3 The MSE, bias and relative bias of different methods of optimal cut-point selection when data generated under bigamma distributions with equal/unequal sample size from diseased (D) and non-diseased (ND) according to degree of overlap/accuracy

From: Comparison of methods of optimal cut-point selection for biomarkers in diagnostic medicine: a simulation study with application of clinical data in health informatics

Equal sample size1

Degree of Overlap

Sample size

Youden index

Euclidian index

Product method

Index of Union

Diagnostic odds ratio

D = ND

MSE

Bias

R.B

MSE

Bias

R.B

MSE

Bias

R.B

MSE

Bias

R.B

MSE

Bias

R.B

Low

50

0.5859

− 0.1071

− 0.0441

0.1371

− 0.0004

− 0.0002

0.2103

0.0196

0.0091

0.0770

− 0.1705

− 0.0772

1471.9

− 38.257

− 0.9507

100

0.4081

− 0.0743

− 0.0306

0.0777

0.0176

0.0083

0.1084

0.0187

0.0087

0.0537

− 0.1516

− 0.0686

1449.5

− 37.921

− 0.9424

200

0.2725

− 0.0479

− 0.0197

0.0469

0.0171

0.0080

0.0670

0.0169

0.0078

0.0410

− 0.1423

− 0.0644

1420.2

− 37.482

− 0.9315

Moderate

50

0.5225

− 0.1103

− 0.0398

0.1534

0.0018

0.0007

0.2263

0.0172

0.0068

0.1590

− 0.2720

− 0.1034

1506.7

− 38.726

− 0.9624

100

0.3140

− 0.0545

− 0.0197

0.0872

0.0155

0.0063

0.1513

0.0432

0.0171

0.1180

− 0.2455

− 0.0934

1497.4

− 38.581

− 0.9588

200

0.2175

− 0.0235

− 0.0085

0.0498

0.0092

0.0037

0.0851

0.0307

0.0121

0.0831

− 0.2027

− 0.0771

1487.7

− 38.423

− 0.9549

High

50

0.5156

− 0.1224

− 0.0316

0.2672

0.0140

0.0040

0.4176

− 0.0054

− 0.0054

0.4365

− 0.4156

− 0.1074

1577.0

− 39.684

− 0.9862

100

0.3264

− 0.0723

− 0.0187

0.1556

0.0295

0.0085

0.2726

0.0278

0.0074

0.2632

− 0.3006

− 0.0777

1575.8

− 39.657

− 0.9855

200

0.1990

− 0.0693

− 0.0179

0.0825

0.0208

0.0060

0.1500

− 0.0012

0.0003

0.1527

− 0.2242

− 0.0579

1574.1

− 39.626

− 0.9848

Unequal sample size1

 

D \(\ne\) ND

MSE

Bias

R.B

MSE

Bias

R.B

MSE

Bias

R.B

MSE

Bias

R.B

MSE

Bias

R.B

Low

50

100

0.5428

− 0.0252

− 0.0104

0.1047

0.0392

0.0185

0.1623

0.0457

0.0211

0.0618

− 0.1407

− 0.0637

1519.8

− 38.889

− 0.9664

50

150

0.5093

− 0.0299

− 0.0123

0.1030

0.0722

0.0340

0.1627

0.0741

0.0343

0.0528

− 0.1292

− 0.0585

1535.6

− 39.097

− 0.9716

50

200

0.5077

0.0444

0.0183

0.1117

0.0617

0.0291

0.1749

0.0882

0.0408

0.0513

− 0.1295

− 0.0586

1555.6

− 39.373

− 0.9785

Moderate

50

100

0.4163

− 0.0318

− 0.0115

0.1334

0.0589

0.0239

0.2073

0.0656

0.0259

0.1285

− 0.2287

− 0.0870

1548.5

− 39.281

− 0.9762

50

150

0.3968

0.0510

0.0184

0.1190

0.0745

0.0303

0.1983

0.0965

0.0382

0.1051

− 0.2000

− 0.0761

1560.1

− 39.432

− 0.9799

50

200

0.4239

0.0658

0.0238

0.1117

0.0662

0.0269

0.1856

0.0733

0.0290

0.1051

− 0.2023

− 0.0769

1575.6

− 39.646

− 0.9852

High

50

100

0.4459

− 0.0482

− 0.0124

0.2211

0.0749

0.0215

0.3740

0.0492

0.0132

0.3226

− 0.3175

− 0.0820

1590.4

− 39.859

− 0.9905

50

150

0.4828

− 0.0031

− 0.0008

0.2002

0.1011

0.0291

0.3835

0.0805

0.0216

0.2805

− 0.2716

− 0.0702

1597.8

− 39.958

− 0.9930

50

200

0.3951

0.0234

0.0060

0.2119

0.1217

0.0350

0.3345

0.0861

0.0231

0.2615

− 0.2527

− 0.0653

1602.7

− 40.023

− 0.9946

  1. \({1. X}_{D}\sim G\left(2,{\beta }_{D}\right)\), \({X}_{ND}\sim G\left(\text{2,1}\right)\), and \({\beta }_{D}\) was taken as 1.5, 2, and 4.5, respectively
  2. MSE: Mean square error, R.B.: Relative bias