| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
1 Department of Biostatistics and Epidemiology and Department of Diagnostic Radiology, The Cleveland Clinic Foundation, 9500 Euclid Ave., Cleveland, OH 44195.
OBJECTIVE. I provide researchers with tables of sample size for multiobserver receiver operating characteristic (ROC) studies that compare the diagnostic accuracies of two imaging techniques.
MATERIALS AND METHODS. I computed the number of patients and
observers needed as a function of five parameters: the measure of diagnostic
accuracy (area under the ROC curve, sensitivity at a false-positive rate 
0.10, or specificity at a false-negative rate 0.10), conjectured level of
accuracy, suspected difference in accuracy between the two imaging techniques,
observer variability, and ratio of patients without to patients with the
condition.
RESULTS. The numbers of patients and observers required vary dramatically with these five parameters, increasing with more refined measures of accuracy, with lower accuracy levels, with smaller suspected differences, with greater observer variability, and with less balanced designs. The number of patients required for a study can be reduced by increasing the number of observers, and vice versa. When the intra- and interobserver variability is large, a study design with just four observers is usually inadequate.
CONCLUSION. Many factors must be considered when determining the appropriate sample sizes for multiobserver ROC studies. My tables serve only as initial ballpark estimates. Investigators should compute sample size using parameters that reflect their clinical application.
CiteULike 
Complore 
Connotea 
Del.icio.us 
Digg 
Reddit 
Technorati What's this?
This article has been cited by other articles:
|
|
 |
|
  References J. ICRU, April 1, 2008; 8(1): 57 - 62. [PDF]
|
|
|
|
 |
|
 L. V. Doering, R. Cross, M. C. Magsarili, L. Y. Howitt, and M. J. Cowan Utility of Observer-Rated and Self-Report Instruments for Detecting Major Depression in Women After Cardiac Surgery: A Pilot Study Am. J. Crit. Care., May 1, 2007; 16(3): 260 - 269. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 N. A. Obuchowski New Methodological Tools for Multiple-Reader ROC Studies Radiology, April 1, 2007; 243(1): 10 - 12. [Full Text] [PDF]
|
|
|
|
 |
|
 G. Natalini, A. Rosano, M. Taranto, B. Faggian, E. Vittorielli, and A. Bernardini Arterial Versus Plethysmographic Dynamic Indices to Test Responsiveness for Testing Fluid Administration in Hypotensive Patients: A Clinical Trial Anesth. Analg., December 1, 2006; 103(6): 1478 - 1484. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. H. Woo, L. P. Henry, J. Krejza, and E. R. Melhem Detection of Simulated Multiple Sclerosis Lesions on T2-weighted and FLAIR Images of the Brain: Observer Performance Radiology, October 1, 2006; 241(1): 206 - 212. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 H Hintze Diagnostic accuracy of two software modalities for detection of caries lesions in digital radiographs from four dental systems. Dentomaxillofac. Radiol., March 1, 2006; 35(2): 78 - 82. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 N. A. Obuchowski ROC Analysis Am. J. Roentgenol., February 1, 2005; 184(2): 364 - 372. [Full Text] [PDF]
|
|
|
|
 |
|
 N. A. Obuchowski, M. L. Lieber, and F. H. Wians Jr. ROC Curves in Clinical Chemistry: Uses, Misuses, and Possible Solutions Clin. Chem., July 1, 2004; 50(7): 1118 - 1125. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
N. A. Obuchowski How Many Observers Are Needed in Clinical Studies of Medical Imaging? Am. J. Roentgenol., April 1, 2004; 182(4): 867 - 869. [Full Text] [PDF]
|
|
|
|
|
|
J. Eng Sample Size Estimation: A Glimpse beyond Simple Formulas Radiology, March 1, 2004; 230(3): 606 - 612. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
