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Determining sample sizes to guarantee variance reductions

 


tex2html_wrap_inline33790 tex2html_wrap_inline33790 Syntax

BD>findsize  :E tex2html_wrap_inline33712

where E is any valid equation which results in a real positive number such that tex2html_wrap_inline39868 .

tex2html_wrap_inline33806 tex2html_wrap_inline33806

The FINDSIZE:  command is used to determine, by exploiting second-order exchangeability, the sample sizes required to guarantee requested levels of variance reduction in individual quantities and the system overall. Suppose that [B/D] currently holds the preliminary adjustment [B/C(n)] as detailed in §16.3. The output consists of the current and maximal resolutions for each tex2html_wrap_inline35510 and for tex2html_wrap_inline34520 overall, together with sample sizes and extra sample sizes to guarantee two alternative degrees of increase in resolution.

For the collection B considered as a whole, a row is output consisting of the following:

  1. the name of the collection, B;
  2. the current resolution in the collection, tex2html_wrap_inline39844 ;
  3. the maximal resolution in the collection, tex2html_wrap_inline39846 ;
  4. the smallest sample size tex2html_wrap_inline39880 such that tex2html_wrap_inline39848 ;
  5. the smallest additional sample sise tex2html_wrap_inline39882 such that tex2html_wrap_inline39850 .

Then, for every element tex2html_wrap_inline35510 (output can be restricted to some subset of elements using the OPTION:  command), a row is output consisting of thhe following.

  1. the name of the element, tex2html_wrap_inline38122 ;
  2. the current resolution in the collection, tex2html_wrap_inline39854 ;
  3. the maximal resolution in the collection, tex2html_wrap_inline39856 ;
  4. the smallest sample size tex2html_wrap_inline39886 such that tex2html_wrap_inline39858 ;
  5. the smallest extra sample size tex2html_wrap_inline39888 such that tex2html_wrap_inline39860 .

Hence, the penultimate column of output consists of sample sizes unconditionally guaranteed to achieve minimum resolutions in uncertainty for the collection and its individual elements. [B/D] indicates whenever the degree of resolution required is not achievable. The final column relates to effects in addition to the current adjustment, and shows the extra sample sizes required to guarantee extra degrees of resolution.

The kind of unconditional output seen in the penultimate column can be accessed for both the collection and its component elements by using the findsize  operator.  


next up previous contents index
Next: Exploring the effects of Up: Exchangeable sequences Previous: Choosing the initial sample

David Wooff
Wed Oct 21 15:14:31 BST 1998