title: Sample size requirements for case-control study designs.
abstract: BACKGROUND
  Published formulas for case-control designs provide sample sizes required to determine that a given disease-exposure odds ratio is significantly different from one, adjusting for a potential confounder and possible interaction.
  
  
  RESULTS
  The formulas are extended from one control per case to F controls per case and adjusted for a potential multi-category confounder in unmatched or matched designs. Interactive FORTRAN programs are described which compute the formulas. The effect of potential disease-exposure-confounder interaction may be explored.
  
  
  CONCLUSIONS
  Software is now available for computing adjusted sample sizes for case-control designs.
authors.affiliation: Division of Clinical Epidemiology, Royal Victoria Hospital, Montreal, Quebec, Canada. michael.edwardes@clinepi.mcgill.ca
authors.forename: M D
authors.initials: MD
authors.lastname: Edwardes
mesh_terms: D016022:Case-Control Studies; D015233:Models, Statistical; D012107:Research Design / Q000706:statistics & numerical data*; D018401:Sample Size; D012984:Software / Q000706:statistics & numerical data