Reliance on evidence – based practices has become important in many a r eas of p r ofessional work, including medical, mental health and fo r ensic practices. It is not likely that emphasis on the im – portance of evidence – based practices will be r educed in the futu r e. Questions about evidence – based practices include questions about the r eliability, criterion validity, and r ep r oducibility of a polygraph test r esult. Polygraph methods that continue to emphasize subjectivity, arbitrary p r ocesses, p r o – cedu r es that cannot be tested and evaluated against an exte r nal criterion, techniques that depend heavi ly on un – r ep r oducible human intuition, guesswork, and methods that cannot confo r m to r ecog – nizable science will ultimately come to be seen as a liability and haza r d to the polygraph p r ofession and to those communities and agencies served by the polygraph p r ofession. This paper describes a simple analytic theory or hypothesis for the comparison question polygraph test. Discussion ad – d r esses a number of a r eas of field practice for which additional r esea r ch is needed, including confi r – matory testing, statement tests, affi r mative answer tests, and testing the limits of admitted behavio r