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Adjusted expectations

 

The adjusted expectations are approximately

eqnarray640

These quantities, which are constructed solely from belief specifications, are functions of the (unobserved) data; informally they are akin to estimators in the traditional sense.gif Generally speaking, it is difficult to tell whether a small coefficient truly indicates unimportance because of the different expectations and scalings of tex2html_wrap_inline8546 and tex2html_wrap_inline8550 . For this reason, we also examine the standardised adjusted expectations, being approximately

eqnarray652

tex2html_wrap_inline8840 is our general notation for the standardised representation of a quantity. Now each coefficient multiplies a quantity that has expectation zero and variance unity, so that the coefficients are more readily comparable. (The constants added in each case are the initial expectations for tex2html_wrap_inline8580 and tex2html_wrap_inline8582 .) We see that the adjusted expectation for tex2html_wrap_inline8580 depends essentially on tex2html_wrap_inline8546 , plus a base value of 4.16; whereas the adjusted expectation for tex2html_wrap_inline8582 depends upon a rather larger base value, plus essentially an average of the before-and-after blood-glucose readings.



David Wooff
Thu Oct 15 12:20:04 BST 1998