retcopper wrote on May 23^rd, 2006 at 2:34pm:

George: While giving  pre employment exams some examiners will do a global evaluation where  the subject might fail one relevant out of three or 4 and still pass.  This evaluation is done by  considering all of the  other pertinent material such as pre and post test interviews and any other background material available.

What this essentially boils down to is that some polygraphers are willing to fudge their scoring to go with their gut. While some applicants may benefit from such fudging, those who don't "pass" the polygraph (with or without the application of a fudge factor) don't get hired.