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Ohashi, El-Khoury, Bennett et al. (2005)

Reader and case sample combinations needed for 0.80 power based on the data of:

Ohashi K, El-Khoury GY, Bennett DL, Restrepo JM, Berbaum KS. Orthopedic hardware complications diagnosed with multi-detector row CT. Radiology 2005;237:570-577.

Readers: 2 pediatric radiologists

Cases: 44 patients, 18 with clinically proven hardware complications, 26 with clinically proven absence of hardware complications

Rating: probability of abnormality on a 100-point subjective probability scale Conditions: (1) radiography, (2) multi-detector row CT

Results: Fixed Reader / Random Case Analysis

 

ROC Model = propROC, Parameter = AUC,

AUCs = 0.842, 0.999, respectively.

Readers = 2, Cases = 44,

MS( Treatment*Reader ) = 0.03649473,

MS( Treatment*Case ) = 0.20259783,

MS( Treatment*Reader *Case ) = 0.03236510.

 

AUC Difference = 0.03

Readers

Readers

and Cases

Random

Cases

Random

Readers

Random

3

.

1675

.

4

.

1628

.

5

.

1600

497

6

.

1581

260

7

.

1568

176

8

1997

1558

134

9

1918

1550

108

10

1861

1543

90

11

1818

1538

78

12

1784

1534

68

13

1756

1530

61

14

1733

1527

55

15

1714

1525

50

Note: Cells containing a period indicate that more than 2000 cases would be required.

 

AUC Difference = 0.05

Readers

Readers

and Cases

Random

Cases

Random

Readers

Random

3

842

605

1379

4

714

588

178

5

664

578

94

6

637

571

64

7

620

566

48

8

607

562

39

9

598

559

33

10

591

557

28

11

586

555

25

12

581

554

22

13

577

553

20

14

574

551

20

15

571

550

20

 

AUC Difference = 0.10

Readers

Readers

and Cases

Random

Cases

Random

Readers

Random

3

163

153

87

4

154

149

33

5

149

146

20

6

147

145

20

7

145

143

20

8

143

142

20

9

142

142

20

10

141

141

20

11

141

141

20

12

140

140

20

13

140

140

20

14

139

140

20

15

139

139

20

 

AUC Difference = 0.20

Readers

Readers

and Cases

Random

Cases

Random

Readers

Random

3

39

40

20

4

38

39

20

5

37

38

20

6

36

38

20

7

36

38

20

8

36

37

20

9

35

37

20

10

35

37

20

11

35

37

20

12

35

37

20

13

35

37

20

14

35

37

20

15

35

37

20

 


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