title: Four decades of research on the effects of detracking reform: where do we stand?--a systematic review of the evidence.
abstract: OBJECTIVE
  To review and synthesize evidence about academic and non-academic effects of detracking reform.
  
  
  METHODS
  Fifteen studies conducted from 1972 to 2006 were located and reviewed, including 4 experimental studies, 2 quasi-experimental studies, 7 observational studies, and 2 qualitative studies. Meta-analyses using fixed effects and random effects models were conducted for all and subsets of selected studies (by the academic ability of students and research design), followed by extensive discussion of individual studies.
  
  
  RESULTS
  Generally speaking, students in detracked groups performed slightly better academically than their equivalent-ability peers in tracked groups (d = 0.087, k = 22, N = 15,577, p < 0.0001), using a fixed effects model. A random effects model also indicated the overall positive effects of detracking (d = 0.202, k = 22, N = 15,577, p < 0.01). However, the effect sizes of individual studies are generally heterogeneous with I(2)(21) = 94.033. Using a random effects model, the study shows that average or high ability students in detracked groups performed no differently than their equivalent-ability peers in tracked groups with a 95% confidence interval of (-0.047, 0.388). For low-achieving students, both the fixed effects model [d = 0.113, k = 8, p < 0.0001, 95% CI (0.056, 0.169)] and random effects model [d = 0.283, k = 8, p < 0.005, 95% CI (0.087, 0.479)] revealed positive effects of detracking on student achievement for the 8 low-ability subgroups in 6 studies. The evidence with respect to the non-academic impact of detracking is mixed.
  
  
  CONCLUSIONS
  The findings suggest that the detracking reform had appreciable effects on low-ability student achievement and no effects on average and high-ability student achievement. Therefore, detracking should be encouraged, especially in schools where the lower-track classes have been traditionally assigned fewer resources.
authors.affiliation: Center for Research and Evaluation in Social Policy, University of Pennsylvania, USA. nrui@dolphin.upenn.edu
authors.forename: Ning
authors.initials: N
authors.lastname: Rui
mesh_terms: D004493:Education / Q000379:methods*; D006801:Humans; D013334:Students