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Table 5 Power of three different logistic regression models for a single binary outcome, under different sample sizes, \(\rho _{XY}\) and \(\rho _X\)

From: The optimal pre-post allocation for randomized clinical trials

 

Model 1 (\(X_2\))

Model 2 (\(X_{\text {log}}\))

Model 3 \((X_{C})\)

Model 1 (\(X_2\))

Model 2 (\(X_{\text {log}}\))

Model 3 \((X_{C})\)

 

\(n_0=n_1=50\)

\(n_0=n_1=75\)

\(\rho _{XY}=0.5, \rho _X=0.6\)

0.5482

0.5662

-

0.7268

0.7509

0.749

\(\rho _{XY}=0.5, \rho _X=0.7\)

0.5474

0.5624

-

0.7264

0.7454

0.7444

\(\rho _{XY}=0.5, \rho _X=0.8\)

0.5476

0.5584

-

0.7262

0.7394

0.7405

\(\rho _{XY}=0.5, \rho _X=0.9\)

0.5464

0.555

-

0.7292

0.7361

0.7341

\(\rho _{XY}=0.6, \rho _X=0.7\)

0.5708

0.5946

-

0.754

0.7788

0.779

\(\rho _{XY}=0.6, \rho _X=0.8\)

0.5692

0.5896

-

0.7538

0.7732

0.771

\(\rho _{XY}=0.6, \rho _X=0.9\)

0.5668

0.5804

-

0.7558

0.767

0.7664

\(\rho _{XY}=0.7, \rho _X=0.8\)

0.6042

0.638

-

0.7888

0.819

0.818

\(\rho _{XY}=0.7, \rho _X=0.9\)

0.6028

0.6263

-

0.7889

0.808

0.8078

 

\(n_0=n_1=100\)

\(n_0=n_1=125\)

\(\rho _{XY}=0.5, \rho _X=0.6\)

0.8442

0.859

0.859

0.9134

0.9272

0.9261

\(\rho _{XY}=0.5, \rho _X=0.7\)

0.8426

0.8567

0.8558

0.9134

0.9244

0.9242

\(\rho _{XY}=0.5, \rho _X=0.8\)

0.8442

0.8536

0.8524

0.9134

0.9211

0.9213

\(\rho _{XY}=0.5, \rho _X=0.9\)

0.8418

0.8488

0.8489

0.9129

0.9182

0.9176

\(\rho _{XY}=0.6, \rho _X=0.7\)

0.8642

0.8864

0.8853

0.9288

0.9433

0.9428

\(\rho _{XY}=0.6, \rho _X=0.8\)

0.8644

0.8811

0.8804

0.9285

0.9396

0.9389

\(\rho _{XY}=0.6, \rho _X=0.9\)

0.8646

0.8765

0.875

0.9292

0.9354

0.9346

\(\rho _{XY}=0.7, \rho _X=0.8\)

0.8924

0.914

0.9139

0.9458

0.9598

0.9592

\(\rho _{XY}=0.7, \rho _X=0.9\)

0.892

0.9064

0.9058

0.9447

0.9552

0.954

 

\(n_0=n_1=150\)

   

\(\rho _{XY}=0.5, \rho _X=0.6\)

0.9536

0.9618

0.9608

   

\(\rho _{XY}=0.5, \rho _X=0.7\)

0.9529

0.9598

0.9587

   

\(\rho _{XY}=0.5, \rho _X=0.8\)

0.9522

0.9576

0.9571

   

\(\rho _{XY}=0.5, \rho _X=0.9\)

0.9531

0.9554

0.955

   

\(\rho _{XY}=0.6, \rho _X=0.7\)

0.9658

0.9732

0.9733

   

\(\rho _{XY}=0.6, \rho _X=0.8\)

0.9643

0.9714

0.9711

   

\(\rho _{XY}=0.6, \rho _X=0.9\)

0.963

0.9683

0.9679

   

\(\rho _{XY}=0.7, \rho _X=0.8\)

0.9756

0.9834

0.9833

   

\(\rho _{XY}=0.7, \rho _X=0.9\)

0.9748

0.9815

0.9808

  Â