Restricted randomization: Difference between revisions

Revision as of 17:30, 26 March 2012

Revision as of 17:41, 26 March 2012

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{{Lead rewrite|date=September 2009}}

In statistics, '''restricted randomization''' occurs in [[experimental design]]s with more than one source of [[statistical dispersion|variability]].

Many [[process (engineering)|processes]] have more than one source of [[statistical dispersion|variation]] in them. In order to [[variance reduction|reduce variation]] in processes, these multiple sources must be understood, and that often leads to the concept of nested or hierarchical data structures. For example, in the semiconductor industry, a [[batch production|batch process]] may operate on several [[wafer (electronics)|wafers]] at a time (wafers are said to be '''nested''' within batch). Understanding the input variables that control variation among those wafers, as well as understanding the variation across each wafer in a run, is an important part of the strategy for minimizing the total variation in the system.

Many [[process (engineering)|processes]] have more than one source of [[statistical dispersion|variation]] in them. In order to [[variance reduction|reduce variation]] in processes, these multiple sources must be understood, and that often leads to the concept of nested or hierarchical data structures. For example, in the semiconductor industry, a [[batch production|batch process]] may operate on several [[wafer (electronics)|wafers]] at a time (wafers are said to be '''nested''' within batch). Understanding the input variables that control variation among those wafers, as well as understanding the variation across each wafer in a run, is an important part of the strategy for minimizing the total variation in the system.

==Example of nested data==