Table 3: Autoregressive integrated moving average (ARIMA) results for monthly overall call volume and number of new callers receiving treatment over 48 months

Parameter	Monthly call volume		New callers per month
Parameter	Estimate (SE)	p value	Estimate (SE)	p value
Intervention
Baseline*	869.79 (55.40)	< 0.001	152.81 (20.68)	< 0.001
New policy for health warning labels† (March 2012-December 2013)	1390.62 (108.94)	< 0.001	267.02 (40.03)	< 0.001
Sustainability‡ (October 2012-December 2013)	−1018.99 (113.54)	< 0.001	−145.04 (40.64)	0.001
Other events
Driven to Quit Challenge§	1087.37 (130.43)	< 0.001	168.36 (32.88)	< 0.001
January effect¶	433.17 (117.35)	0.001	135.80 (29.22)	< 0.001
Autoregressive parameter	0.175 (0.169)	0.3	0.460 (0.163)	0.007
Model diagnostics
Stationary R²	0.87		0.82
Root-mean-square error	212.25		55.36

Note: SE = standard error.

*Constant in model (the average monthly call volume and new callers per month, adjusted for months with no intervention and no Driven to Quit Challenge or January effect).

†Additional average monthly call volume and new callers per month over baseline for March 2012-December 2013.

‡Average monthly reduction in call volume and new callers per month from peak months of March 2012-September 2012.

§Equal to 1 for months during which promotion campaign occurred (February 2010, 2011 and 2012) and 0 otherwise.

¶Equal to 1 in January and 0 otherwise.