You take a few puffs and you're high, maybe you take only one, but you're high just the same.
Through years of dealing with marijuana users (and having been one myself), I've not seen it to be
about the amount, but rather the quality. I've been amongst those to smoke for hours consecutively, and never get
as high as i was up until the first contact set in.
I have no links, anyone chime in here, these are my own
personal experiences.
I believe measuring this will be difficult, aside from looking for how red/closed/open the
individuals eyes are, yet different strains produce different affects...