title: The use of cohort vs repeated cross-sectional sample survey data in monitoring changing breast cancer screening practices.
abstract: BACKGROUND
  The method used to select a study sample is a key element in designing a research protocol. This article explores two of the more common methods used, focusing on the relative advantages and disadvantages of each one.
  
  
  METHODS
  Both cohort and repeated, independent cross-sectional surveys were conducted in each of 3 years (1988-1990) in the Awareness of Breast Cancer Screening Project to follow changing breast cancer screening rates among a population of women 50-75 years of age on Long Island, New York.
  
  
  RESULTS
  Both survey methods revealed statistically significant increases in self-reports of mammography use. The cohort and repeated cross-sectional survey sample responses to questions concerning knowledge, attitudes, and behavior regarding breast cancer screening were comparable. An educational effect of the baseline survey itself on the cohort was not seen.
  
  
  CONCLUSIONS
  Each of the two survey methods has advantages and disadvantages with respect to the other. The cohort method permits examination of changes in the same individual over time and is less costly and less time-consuming to perform. On the other hand, the cross-sectional method does not suffer from cumulative losses in respondents with repeated surveys and better reflects the changing community. The study findings can be used to guide the selection of an appropriate survey methodology for monitoring breast cancer screening practices in other settings.
authors.affiliation: Department of Preventive Medicine, State University of New York at Stony Brook 11794-8036, USA.
authors.forename: L S
authors.initials: LS
authors.lastname: Caplan
authors.forename: D S
authors.initials: DS
authors.lastname: Lane
authors.forename: R
authors.initials: R
authors.lastname: Grimson
mesh_terms: D000368:Aged; D015982:Bias; D001943:Breast Neoplasms / Q000517:prevention & control*; D015331:Cohort Studies; D003365:Costs and Cost Analysis; D003430:Cross-Sectional Studies; D003625:Data Collection; D005260:Female; D007722:Health Knowledge, Attitudes, Practice; D006801:Humans; D008327:Mammography / Q000706:statistics & numerical data; D008403:Mass Screening / Q000379:methods* / Q000706:statistics & numerical data; D008875:Middle Aged; D010808:Physical Examination / Q000706:statistics & numerical data; D012107:Research Design