Table 2

Estimated percentage point changes in mean cigarette consumption per day as a function of e-cigarette use and NRT use among smokers for cutting down from November 2006 to March 2016, based on ARIMAX models

All users of nicotine replacementOnly daily users of nicotine replacement
Percentage change per  1  %  change in the exposure (95%   CI)  P values
Use of e-cigarettes for cutting down
(immediate impact)
−0.010 (−0.024 to 0.005)
0.191
−0.010 (−0.025 to 0.005)
0.191
−0.008 (−0.023 to 0.006) 0.256−0.009 (−0.024 to 0.006) 0.229
NRT use for cutting down
(immediate impact)
0.002 (−0.033 to 0.037) 0.9170.006 (−0.030 to 0.043)
0.732
−0.002 (−0.016 to 0.013)
0.825
−0.002 (−0.017 to 0.013) 0.786
Mass media expenditure
(immediate impact)
<0.001 (−0.001 to 0.001)
0.885
<0.001 (−0.001 to 0.001) 0.860
Total percentage change due to the exposure (95% CI) P values
Smoking ban
(pulse effect)
0.014 (−0.072 to 0.099)
0.755
0.012 (−0.073 to 0.097)
0.782
Increase in age-of-sale
(pulse effect)
−0.043 (−0.128 to 0.042)
0.323
−0.042 (−0.127 to 0.043) 0.329
Move to local authority control
(pulse effect)
−0.025 (−0.110 to 0.061)
0.571
−0.029 (−0.115 to 0.056) 0.499
Licensing for NRT for harm reduction
(pulse effect)
0.018 (−0.072 to 0.108)
0.694
0.015 (−0.074 to 0.103) 0.747
NICE guidance on harm reduction
(pulse effect)
−0.028 (0.058 to <0.001)
0.529
−0.027 (−0.112 to 0.059) 0.541
Best fitting modelARIMAX(0,1,1)(0,0,0)12 ARIMAX(0,1,1)(0,0,0)12 ARIMAX(0,1,1)(0,0,0)12 ARIMAX(0,1,1)(0,0,0)12 ARIMAX(0,1,1)(0,0,0)12 ARIMAX(0,1,1)(0,0,0)12
Non-seasonal AR p valuesNANANANANANA
Non-seasonal MA p values<0.001<0.001<0.001<0.001<0.001<0.001
Seasonal AR p valuesNANANANANANA
Seasonal MA p valuesNANANANANANA
R2 0.640.640.650.640.640.65
Bayes factor e-cigarette (0.009 (0.1))1.87 (0.34)1.79 (0.32)1.46 (0.23)1.61 (0.27)
Bayes factor NRT (0.009 (0.1))0.86 (0.16)0.81 (0.15)0.76 (0.10)0.76 (0.10)
  • An AR(1) means that the value of a series at one point in time is the sum of a fraction of the value of the series at the immediately preceding point in time and an error component; an MA(1) means that the value of a series at one point in time is a function of a fraction of the error component of the series at the immediately preceding point in time and an error component at the current point in time.

  • AR, autoregressive; ARIMAX, Autoregressive Integrated Moving Average with Exogeneous Input; MA, moving average; NA, not applicable; NICE, National Institute for Health and Care Excellence; NRT, nicotine replacement therapy.