Given both gold standards but not all of the additional information linking the two (i.e., actual length of time over which the alcohol was consumed, pattern of drinking, food consumption, etc.), there may be considerable variation in the strength of their relationship. This may be especially true if larger quantities consumed are associated with longer (but unknown) time periods and more variable patterns of consumption, as these are two variables that are very influential on the underlying BAC curve over time. That is, the gold standards (either self-report or BAC) must consist of more than just themselves alone for them to actually be considered equivalent (i.e., to be able to move from one to the other).
