Uncertain facts and inexact rules can be represented and processed in standard Prolog through meta-interpretation. This requires the specification of appropriate parsers and belief calculi. We present a meta-interpreter that takes a rule-based belief calculus as an external variable. The certainty-factors calculus and a heuristic Bayesian belief-update model are then implemented as stand-alone ...

INTRODUCTION Information on external validity enables public health practitioners to generalize conclusions about an intervention to future or different conditions and is critical to moving research into practice. Prior reviews examining external validity focused on efficacy publications only. Our objective was to determine the extent to which secondary articles could enhance information about ...

BACKGROUND External validity of study results is an important issue from a clinical point of view. From a methodological point of view, however, the concept of external validity is more complex than it seems to be at first glance. METHODS Methodological review to address the concept of external validity. RESULTS External validity refers to the question whether results are generalizable to p...