Polygraph vs anxiety ... how many tests?

[Howmanyistilthetruthisout]

I'm tossed, if a polygraph is not always accurate but can be sometimes, shouldn't you get an accurate reading after 4-5 tests?  I know someone who's taken it 4 times and failed all of them.  Is she being dishonest or can anxiety make her fail over and over again?

[George W. Maschke]

Polygraph testing has no scientific basis and is inherently biased against the truthful. It is not at all odd that a truthful person might repeatedly fail a polygraph "test" because although the procedure is invalid, it's not like a coin toss. One would fully expect a truthful person who has been sensitized to the relevant questions to "fail."

No inferences regarding a person's truthfulness or lack thereof can be safely drawn based on polygraph chart readings.