Comment by gwern

> That is, assuming a 1-pack-a-day smoker of a 0.6mg / cigarette brand ...

IIRC, the effective dose of a smoker is going to be both quantitatively larger due to more efficient absorption through the lungs and also qualitatively different due to the much faster absorption.

Also, I should mention that in the experiment, half the days were placebos, so that's at least 5 pieces of gum which were allowed to dry out, reducing the average a little bit.