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Table 4 Designs with maximal power of detecting the interaction, according to sensitivity and specificity

From: Flexible Two-Phase studies for rare exposures: Feasibility, planning and efficiency issues of a new variant

Gene-surrogate

Flexible two-phase design options

Expected Phase One counts

Power#

Cost*

Spec

Sens

n0

n1

ρ0

ρ1

N0

N1

  

70%

80%

800

400

90%

90%

5902

1373

83%

1564

70%

90%

800

400

90%

90%

5882

1325

87%

1560

80%

60%

800

400

90%

90%

8824

1988

87%

1741

80%

70%

800

400

90%

90%

8780

1889

91%

1733

80%

80%

800

400

90%

90%

8738

1800

94%

1727

80%

90%

800

400

90%

90%

8696

1718

96%

1720

90%

60%

900

300

90%

90%

19286

2000

98%

2264

90%

70%

900

300

90%

90%

19104

2000

99%

2255

90%

80%

900

300

90%

90%

18925

1960

99.6%

2244

90%

90%

900

300

90%

90%

18750

1835

99.8%

2229