### abstract ###
research endeavors to determine the effectiveness of patient decision aids ptdas have yielded mixed results
the conflicting evaluations are largely due to the different metrics used to assess the validity of judgments made using ptdas
the different approaches can be characterized by hammond's  CITATION  two frameworks for evaluating judgments  correspondence and coherence
this paper reviews the literature on the effectiveness of ptdas and recasts this argument as a renewed debate between these two meta-theories of judgment
evaluation by correspondence criteria involves measuring the impact of patient decision aids on metrics for which there are objective  external  and empirically justifiable values
evaluation on coherence criteria involves assessing the degree to which decisions follow the logical implications of internal  possibly subjective  value systems preferences
coherence can exist absent of correspondence and vice versa
therefore  many of the seemingly conflicting results regarding the effectiveness of ptdas can be reconciled by considering that the two meta-theories contribute unique perspectives
we argue that one approach cannot substitute for the other  and researchers should not deny the value of either approach
furthermore  we suggest that future research evaluating ptdas include both correspondence and coherence criteria
### introduction ###
in  NUMBER   kenneth hammond argued that the field of judgment and decision making has taken two distinct paths  describing those two paths as meta-theories used in the evaluation of judgments
in the correspondence meta-theory  judgments are compared to objective facts with the explicit goal of evaluating the empirical accuracy of the judgments
in contrast  the coherence meta-theory assesses the logical consistency of judgments
in this framework  judgments are evaluated by the degree to which they are similar to solutions given by logical  mathematical  or statistical theories
judgments are not compared to an external  true  value  instead judgments are compared to a normative rule  often mathematical in nature
