title: Pitfalls in subgroup analysis based on growth mixture models: a commentary on Van Leeuwen et al. (2012).
abstract: OBJECTIVE
  This article is a brief commentary in response to "van Leeuwen et al. (Qual Life Res 21:1499-1508, 2012)"
  
  
  RESULTS
  The commentary argues that in the context of mixture modeling, assigning individuals to specific subgroups for conducting a secondary set of analyses ignores the original uncertainty in group membership, thereby biasing any subsequent results and inference.
  
  
  CONCLUSIONS
  Alternative approaches to subgroup analysis that attempt to preserve uncertainty in group membership are discussed and illustrated.
authors.affiliation: National Crime Prevention Centre, Public Safety Canada, 269 Laurier Avenue West, Ottawa, ON, K1A 0P8, Canada, cameron.mcintosh@ps-sp.gc.ca.
authors.forename: Cameron N
authors.initials: CN
authors.lastname: McIntosh
mesh_terms: D000223:Adaptation, Psychological; D005260:Female; D006801:Humans; D007297:Inpatients / Q000523:psychology*; D008297:Male; D010549:Personal Satisfaction; D011788:Quality of Life / Q000523:psychology*; D015983:Selection Bias; D013119:Spinal Cord Injuries / Q000523:psychology*