Originally posted by tHeGiNo
They are capable to determine when and how much you have smoked, if I am not mistaken.
You are mistaken. they can only tell the levels in you system. Some one who never smoked pot and went out and smokes a big fat joint may test along the same lines as as a heave toker is tested the next day. also a moth to clean out is a rough estimate. I know a guy who tested positive after 6 weeks of being clean. he smoke close to half an oz a week.