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Table 37 Performance of tolerance intervals based on gamma distribution when the true distribution is lognormal (G: Gamma; F: Lognormal)

From: Tolerance intervals in statistical software and robustness under model misspecification

  

n = 10

n = 25

n = 50

n = 100

n = 10

n = 25

n = 50

n = 100

  

ρ= 0.9

   

ρ= 0.95

   

α = 0.01

\(\hat {\alpha }\)

0.0159

0.0155

0.0142

0.0091

0.0183

0.0185

0.0180

0.0133

 

\(\hat {\rho }\)

0.9879

0.9743

0.9616

0.9490

0.9947

0.9893

0.9836

0.9775

 

\(\hat {s}\)

0.0260

0.0231

0.0207

0.0172

0.0159

0.0126

0.0114

0.0098

α= 0.05

\(\hat {\alpha }\)

0.0775

0.0642

0.0562

0.0488

0.0831

0.0742

0.0669

0.0619

 

\(\hat {\rho }\)

0.9680

0.9561

0.9460

0.9366

0.9843

0.9800

0.9754

0.9706

 

\(\hat {s}\)

0.0466

0.0326

0.0257

0.0197

0.0305

0.0196

0.0153

0.0119

α= 0.1

\(\hat {\alpha }\)

0.1407

0.1221

0.1004

0.0933

0.1472

0.1344

0.1176

0.1108

 

\(\hat {\rho }\)

0.9514

0.9438

0.9364

0.9293

0.9747

0.9732

0.9700

0.9664

 

\(\hat {s}\)

0.0592

0.0378

0.0283

0.0210

0.0405

0.0238

0.0175

0.0130

α= 0.2

\(\hat {\alpha }\)

0.2640

0.2238

0.1971

0.1778

0.2716

0.2395

0.2174

0.1996

 

\(\hat {\rho }\)

0.9254

0.9266

0.9238

0.9201

0.9586

0.9630

0.9625

0.9609

 

\(\hat {s}\)

0.0744

0.0440

0.0313

0.0225

0.0541

0.0293

0.0203

0.0145

  

ρ= 0.99

   

ρ= 0.995

   

α = 0.01

\(\hat {\alpha }\)

0.0450

0.0698

0.0923

0.1367

0.0566

0.1061

0.1650

0.2684

α= 0.01

\(\hat {\alpha }\)

0.0253

0.0330

0.0446

0.0569

0.0295

0.0434

0.0630

0.1008

 

\(\hat {\rho }\)

0.9988

0.9979

0.9967

0.9952

0.9993

0.9988

0.9982

0.9973

 

\(\hat {s}\)

0.0069

0.0039

0.0034

0.0029

0.0053

0.0025

0.0021

0.0018

α= 0.05

\(\hat {\alpha }\)

0.1027

0.1190

0.1300

0.1615

0.1133

0.1462

0.1766

0.2383

 

\(\hat {\rho }\)

0.9957

0.9954

0.9945

0.9934

0.9972

0.9973

0.9968

0.9961

 

\(\hat {s}\)

0.0142

0.0068

0.0050

0.0038

0.0110

0.0046

0.0033

0.0024

α= 0.1

\(\hat {\alpha }\)

0.1805

0.1952

0.2063

0.2418

0.1970

0.2335

0.2743

0.3458

 

\(\hat {\rho }\)

0.9924

0.9934

0.9929

0.9922

0.9950

0.9960

0.9958

0.9954

 

\(\hat {s}\)

0.0198

0.0089

0.0060

0.0043

0.0155

0.0061

0.0040

0.0028

α = 0.2

\(\hat {\alpha }\)

0.3116

0.3176

0.3402

0.3725

0.3352

0.3686

0.4173

0.4913

 

\(\hat {\rho }\)

0.9861

0.9902

0.9907

0.9905

0.9906

0.9939

0.9944

0.9943

 

\(\hat {s}\)

0.0283

0.0119

0.0075

0.0051

0.0224

0.0084

0.0051

0.0034

  1. The bolded values are \({\hat \alpha }\) within \(\pm 2 \sqrt {\alpha (1-\alpha)/M}\) and \({\hat \rho }\) within \(\pm 2 \sqrt {\rho (1-\rho)/M}\)