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Bayesian Experimental Design - Mathematical Sciences Home Pages

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(1993)showedbysimulationthatthe<strong>Bayesian</strong>criteriadowellempirically.Clyde(1993) alsopresentedsomesimulations.ArecentpaperbySun,TsutakawaandLu(1995)showed bysimulationthatthenumericalapproximationofTsutakawa(1972)fordesignintheone parameterlogisticregressionexampleisremarkablyaccurate.<br />

notalwaysbeenfullyunderstood.ForexampleAtkinsonandDonev(1992)present\Five nosingleapproachcancomfortablybelabeledasthedenitive\<strong>Bayesian</strong>nonlineardesign criterion".Thecriteriaderivedinthissectionareallapproximationstotheideal.Thishas 4.6Discussion<br />

versionsof<strong>Bayesian</strong>D-optimality"inTable19.1.Theyexplainthatthe(15)corresponds Apartfromtheidealapproachofmaximizingexactexpectedutilitypreciselyasinsay(1),<br />

to\pre-posteriorexpectedloss"butdonotexplainthatitisShannoninformationasutility ratherthanloss,anditisanapproximation.<br />

suchasthosegivenby(15)whicharetheexpectation,overapriordistributionofalocal 5.1Introduction 5Optimalnonlinear<strong>Bayesian</strong>design<br />

optimalitycriterion.Werefertosuchcriteriaas\<strong>Bayesian</strong>designcriteria".Thesedesign criteriaareconcaveonH,thespaceofallprobabilitymeasuresonX.Subjecttosome regularityconditions,anequivalencetheoremcanbederived.Theequivalencetheoremwas Chaloner(1987)andChalonerandLarntz(1986,1988,1989)developedtheuseofcriteria<br />

statedbyWhittle(1973)inthecontextoflineardesignproblems,butitsapplicationto nonlinearproblemswasnotthenapparentandtheregularityconditionsrequiredforitsuse<br />

designcanbefoundusingnumericaloptimizationandthetheoremmakesiteasytocheck inthenonlinearcasenotstated.SeealsoLauter(1974,1976)andDubov(1977).The<br />

whetherthecandidatedesignisindeedgloballyoptimaloverH. theoremstatesthat,inordertoverifythatadesignmeasureisoptimal,itisnecessaryonly tocheckthattheappropriatedirectionalderivativeatthatdesignmeasure,inthedirectionof allonepointdesignmeasuresiseverywherenonpositive.Acandidateoptimalapproximate Thetheoremappliestoanycriterionthatisanaverage,overapriordistribution,ofa 34

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