Table 4.

Adjusted estimated percentage point changes in quit success rate and overall quit rate as a function of e‐cigarette use during a quit attempt, based on ARIMAX models including the affordability index.

	Quit success rate			Overall quit rate
	Percentage change per 1% change in the exposure	95% CI	P‐value	Percentage change per 1% change in the exposure	95% CI	P‐value
Prevalence of e‐cigarette use during a quit attempt	0.062	0.028 to 0.096	< 0.001	0.085	0.035 to 0.135	0.001
Mass media Affordability	0.072 −0.002	0.031 to 0.113 −0.013 to 0.009	0.001 0.754	0.066 −0.018	−0.001 to 0.124 −0.033 to −0.002	0.055 0.023

	Total change due to the exposure	95% CI	P‐value	Total change due to the exposure	95% CI	P‐value
Smoking ban (temporary impact in third quarter of 2007)	0.363	0.090 to 0.636	0.009	0.442	0.039 to 0.855	0.036
Increase in age of sale (temporary impact in fourth quarter of 2007)	0.325	0.048 to 0.603	0.021	0.265	−0.173 to 0.702	0.235
Move to local authority (temporary impact in second quarter of 2013)	−0.238	−0.508 to 0.033	0.085	−0.143	−0.564 to 0.278	0.506
Tobacco control directive (temporary impact in the second quarter of 2016)	0.226	−0.055 to 0.507	0.115	0.425	0.011 to 0.838	0.044
Model Lag for e‐cigarettes Lag for mass media Lag for affordability Adjusted R 2	ARIMA(0,1,1)(1,0,0)4 None None None 0.51			ARIMA(0,1,1)(1,0,0)4 None None None 0.39

ARIMA = autoregressive integrated moving average analysis; ARIMAX = Autoregressive Integrated Moving Average with Exogeneous Input; CI = confidence interval.