title: Sample size for biomarker studies: more subjects or more measurements per subject?
abstract: OBJECTIVE
  In molecular epidemiologic studies, optimizing the use of available biological specimens while minimizing the cost is always a challenge. This is particularly true in pilot studies, which often have limited funding and involve small numbers of biological samples too small for assessment of recently developed biomarkers.
  
  
  METHODS
  In this study we examined several statistical approaches for determining how many experimental subjects to use in a biomarker study and how many repeated measurements to make on each sample, given specific funding considerations and the correlated nature of the repeated measurements.
  
  
  RESULTS
  A molecular epidemiology study of DNA repair and aging in basal cell carcinoma was used to illustrate the application of the statistical methods proposed.
  
  
  CONCLUSIONS
  Our methods extend traditional designs on biomarker studies with repeated measurements to including funding constraints.
authors.affiliation: Program in Biometry, The University of Texas, School of Public Health, Houston 77030, USA.
authors.forename: Dejian
authors.initials: D
authors.lastname: Lai
authors.forename: Terri M
authors.initials: TM
authors.lastname: King
authors.forename: Lemuel A
authors.initials: LA
authors.lastname: Moyé
authors.forename: Qingyi
authors.initials: Q
authors.lastname: Wei
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging; D015415:Biomarkers / Q000032:analysis*; D002280:Basal Cell Carcinoma / Q000453:epidemiology / Q000235:genetics; D003363:Cost Control; D004260:DNA Repair; D016021:Epidemiologic Studies; D006801:Humans; D008875:Middle Aged; D015203:Reproducibility of Results; D012107:Research Design; D018401:Sample Size
chemical_list: D015415:Biomarkers