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Table 1 Estimated percentage point change in the mean prevalence of e-cigarette use among tobacco smokers who endorse the belief that e-cigarettes are less harmful than combustible cigarettes during the study period (2014–2019), based on autoregressive integrated moving average with exogenous input (ARIMAX) models

From: Association between changes in harm perceptions and e-cigarette use among current tobacco smokers in England: a time series analysis

 Unadjusted (95% CI, p value)Adjusted (95% CI, p value)
Percentage change per 1% change in the mean prevalence of the exposure
 Use of e-cigarettes0.52 (0.30–0.75), < 0.0010.48 (0.25–0.71), < 0.001
 Current cigarette smokers0.08 (− 0.14–0.31), 0.48
 Tried to quit in the past year0.12 (− 0.11–0.36), 0.31
 National mass media expenditure in millions (£)0.10 (− 0.14–0.34), 0.42
Best fitting model
 ARIMAX (p,d,q)(P,D,Q)(0,1,1)(0,0,0)(0,1,1)(0,0,0)
 Non-seasonal (p value)  
  Autoregressive (AR) term
  Moving average (MA) term< 0.001< 0.001
 Pseudo R20.280.33