title: Combining cycles of the Canadian Community Health Survey.
abstract: BACKGROUND
  A single cycle of the Canadian Community Health Survey (CCHS) may not meet researchers' analytical needs. This article presents methods of combining CCHS cycles and discusses issues to consider if these data are to be combined. An empirical example illustrates the proposed methods.
  
  
  METHODS
  Two methods can be used to combine CCHS cycles: the separate approach and the pooled approach. With the separate approach, estimates are calculated for each cycle separately and then combined. The pooled approach combines data at the micro-data level, and the resulting dataset is treated as if it is a sample from one population.
  
  
  RESULTS
  For the separate approach, it is recommended that the simple average of the estimates be used. For the pooled approach, it is recommended that weights be scaled by a constant factor where a period estimate covering the time periods of the individual cycles can be created. The choice of method depends on the aim of the analysis and the availability of data.
  
  
  CONCLUSIONS
  Combining cycles should be considered only if the most current period estimates do not suffice. Both methods will obscure cycle-to-cycle trends and will not reveal changing behaviours related to public health initiatives.
authors.affiliation: Household Survey Methods Division, Statistics Canada, Ottawa, Ontario. Steven.Thomas@statcan.gc.ca
authors.forename: Steven
authors.initials: S
authors.lastname: Thomas
authors.forename: Brenda
authors.initials: B
authors.lastname: Wannell
mesh_terms: D002170:Canada; D003430:Cross-Sectional Studies; D003625:Data Collection / Q000379:methods*; D003627:Data Interpretation, Statistical; D006306:Health Surveys; D006801:Humans; D012107:Research Design