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Adjusting a collection of quantities

We have suggested how we might adjust our prior expectation for any one element of a collection tex2html_wrap_inline3600 using observations on a collection tex2html_wrap_inline3598 . When we evaluate a collection of adjusted expectations { tex2html_wrap_inline3816 , ..., tex2html_wrap_inline3818 }, we also implicitly evaluate the adjusted value for each element of tex2html_wrap_inline3820 , the collection of linear combinations of the elements of B, as, by the linearity of adjusted expectation (equation 2),

equation483

We now analyse changes in beliefs over tex2html_wrap_inline3820 . We consider B, D as vectors, of dimension r and k, respectively. We define the adjusted version of the collection B given D, tex2html_wrap_inline3828 , to be the `residual' vector

displaymath3806

The properties of the adjusted vector are as for a single quantity, namely

  1. equation497

    the r dimensional null vector,

  2. equation500

    the tex2html_wrap_inline3836 null matrix.

Therefore, just as for a single quantity X, we partition the vector B as the sum of two uncorrelated vectors, namely

equation507

so that we may partition the variance matrix of B into two variance components

  equation511

We call

displaymath3807

the resolved variance matrix, for B by D. We call

displaymath3808

the adjusted variance matrix, for B by D.

tex2html_wrap_inline3854 , tex2html_wrap_inline3856 are calculated as in equations 1, 8, namely

  equation533

  equation543

equation554



David Wooff
Thu Oct 15 11:56:54 BST 1998