Confidence intervals and sample size calculations for studies of film-reading performance

A J Scally, S Brealey

Research output: Contribution to journalLiterature reviewpeer-review


The relaxation of restrictions on the type of professions that can report films has resulted in radiographers and other healthcare professionals becoming increasingly involved in image interpretation in areas such as mammography, ultrasound and plain-film radiography. Little attention, however, has been given to sample size determinations concerning film-reading performance characteristics such as sensitivity, specificity and accuracy. Illustrated with hypothetical examples, this paper begins by considering standard errors and confidence intervals for performance characteristics and then discusses methods for determining sample size for studies of film-reading performance. Used appropriately, these approaches should result in studies that produce estimates of film-reading performance with adequate precision and enable investigators to optimize the sample size in their studies for the question they seek to answer.

Original languageEnglish
Pages (from-to)238-246
Number of pages9
JournalClinical Radiology
Issue number3
Publication statusPublished - Mar 2003


  • film-reading performance
  • sample size
  • confidence intervals

Cite this