Three typesofambiguity

For eachofthreetypesofambiguity,wecomputearobustRamseyplanandanassociated worst-case probabilitymodel. Ex post, ambiguityoftypeIimpliesendogenouslydistorted homogeneous beliefs,whileambiguitiesoftypesIIandIIIimplydistorted heterogeneous beliefs.Martingalescharacterizealternativeprobabilityspecificationsandclarifydistinc- tions amongthethreetypesofambiguity.WeuserecursiveformulationsofRamsey problemstoimposelocalpredictabilityofcommitmentmultipliersdirectly.Toreducethe dimensionofthestateinarecursiveformulation,wetransformthecommitmentmultiplier to accommodatetheheterogeneousbeliefsthatarisewithambiguityoftypesIIandIII.Our formulationsfacilitatecomparisonsoftheconsequencesofthesealternativetypesof ambiguity