Optimization of nested step designs

Célia Fernandes, Paulo Ramos, João Tiago Praça Nunes Mexia

Research output: Contribution to journalArticlepeer-review


The number of treatments in a balanced nested design is the product of the number of levels in each factor. This number may be too large. As an alternative, in nested step designs there are as many sub-designs as factors plus one last sub-model used for error estimation. In each sub-design the branching is done only for the corresponding factor. The numbers of treatments is now the sum of the factor levels plus one. Moreover the amount of information for the different factors is more evenly distributed. We present a method to minimize the sum of the estimated variances of the estimators of the variance components.
Original languageEnglish
Pages (from-to)143-155
Number of pages13
JournalBiometrical Letters
Issue number2
Publication statusPublished - 1 Jan 2005


  • Random effects
  • variance components
  • nested factors
  • nested step designs
  • optimization


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