Table 1. Measures.

Measures	Categorizations	Questions and responses used in categorizations
Sample-defining measures (assessed at baseline wave of each wave pair)
Cigarette smoking status	Daily smoker: smokes cigarettes every day	“Do you now smoke cigarettes…” with response options: every day/some days/not at all
Quit intentions	No intentions: does not plan to ever quit cigarettes/tobacco for gooda	“Do you plan to ever quit [cigarettes/tobacco] for good?” with responses options: yes/no
e-Cigarette use status	Nonuser: does not use e-cigarettes at all	“Do you now use [e-cigarettes]…” with response options: every day/some days/not at allb
Predictor measure (assessed at follow-up wave among those who were e-cigarette nonusers at baseline wave)
e-Cigarette use status	(1) No e-cigarette use (2) Nondaily e-cigarette use (3) Daily e-cigarette use	“Do you now use [e-cigarettes]…” with response options: every day/some days/not at allb
Outcome measures (assessed at follow-up wave among those who were daily smokers and had no intentions to quit at baseline wave)
Cigarette discontinuation at follow-up	(1) Cigarette discontinuation: did not smoke in the past 12 mo or is currently smoking not at all (2) Cigarette smoker: is currently smoking every day or some days	“In the past 12 months, have you smoked a cigarette, even 1 or 2 puffs?” with response options: yes/no “Do you now smoke cigarettes…” with response options: every day/some days/not at all
Discontinuing daily cigarette smoking at follow-up	(1) Discontinuing daily cigarette smoking: did not smoke in the past 12 mo, or is currently smoking not at all, or is currently smoking some days (2) Daily cigarette smoker: is currently smoking every day	“In the past 12 months, have you smoked a cigarette, even 1 or 2 puffs?” with response options: yes/no “Do you now smoke cigarettes…” with response options: every day/some days/not at all

^a Cigarette smokers who were current users of any other non–e-cigarette tobacco product and had ever used that tobacco product fairly regularly were asked about intending to quit using tobacco rather than specifically about intending to quit smoking cigarettes.

^b e-Cigarettes refers to all e-products (ie, e-cigarettes, e-cigars, e-pipes, and e-hookah).