Sample size and optimal designs for reliability studies

Stat Med. 1998 Jan 15;17(1):101-10. doi: 10.1002/(sici)1097-0258(19980115)17:1<101::aid-sim727>;2-e.


A method is developed to calculate the required number of subjects k in a reliability study, where reliability is measured using the intraclass correlation rho. The method is based on a functional approximation to earlier exact results. The approximation is shown to have excellent agreement with the exact results and one can use it easily without intensive numerical computation. Optimal design configurations are also discussed; for reliability values of about 40 per cent or higher, use of two or three observations per subject will minimize the total number of observations required.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Analysis of Variance
  • Child
  • Down Syndrome / diagnosis
  • Humans
  • Observer Variation
  • Ontario
  • Psychometrics*
  • Reproducibility of Results*
  • Research Design*
  • Sample Size*