Table 3.

Weighted percentage difference in cost of smoking for sociodemographics and cost-minimising strategies from GAM, stratified by social grade

	Social grade				P value for interaction, high vs low
	Low (n=7032)	Middle (n=8138)		High (n=1797)
	100β with 95% CI	100β with 95% CI	P value for interaction, middle vs low	100β with 95% CI
Age
Per 10 years increase	−0.23 (−1.04 to 0.59)	−0.18 (−0.65 to 1.00)		0.27 (−1.65 to 2.19)
Gender
Male	ref	ref		ref
Female	0.54 (2.10 to 3.18)	0.17 (−2.44 to 2.78)		−1.55 (−7.56 to 4.46)
Factory-made cigarette consumption
Per 10 cigarettes decrease	−11.70 (−11.41 to −11.98)	−13.20 (−12.93 to −13.47)	<0.001	−15.36 (−14.74 to −15.98)	<0.001
RYO cigarette consumption
Per 10 cigarettes decrease	−4.95 (−4.68 to −5.21)	−6.15 (−5.84 to −6.45)	0.007	−7.90 (−7.10 to −8.70)	0.004
Use of illicit sources
No use of illicit sources in last 6 months	ref	ref		ref
Used illicit sources in last 6 months	−12.25 (−16.72 to −7.78)	−7.11 (−12.02 to −2.21)	0.028	−5.63 (−19.09 to 7.84)	0.078
Cross-border purchase
No cross-border purchase in last 6 months	ref	ref		ref
Cross-border purchase in last 6 months	−13.01 (−19.03 to −6.72)	−9.99 (−14.46 to −5.53)	0.264	−7.24 (−15.80 to 1.33)	0.053

All models were adjusted for all variables in the table.

GAM, generalised additive models; RYO, roll -your-own.