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 replacement | Only 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) 0.917 | 0.006 (−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 model | 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 | ARIMAX(0,1,1)(0,0,0)12 |
| Non-seasonal AR p values | NA | NA | NA | NA | NA | NA |
| Non-seasonal MA p values | <0.001 | <0.001 | <0.001 | <0.001 | <0.001 | <0.001 |
| Seasonal AR p values | NA | NA | NA | NA | NA | NA |
| Seasonal MA p values | NA | NA | NA | NA | NA | NA |
| R2 | 0.64 | 0.64 | 0.65 | 0.64 | 0.64 | 0.65 |
| 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.