. Author manuscript; available in PMC: 2019 Oct 21.

Published in final edited form as: Addiction. 2019 Jan 24;114(Suppl 1):6–14. doi: 10.1111/add.14528

Table 4:

Sources and sample sizes for 4CV1 respondents

Country, subsample	Sources	Sample size
AU, smokers/former smokers 18+	ITC 4C cohort (retention rate 43.1%)	515
	Roy Morgan Single Source (probability-based)	504
	Survey Sampling International	485
CA, smokers/former smokers 18+	ITC 4C cohort (retention rate 41.6%)	567
CA, smokers/former smokers 18+	Léger Marketing, where possible from their probability-based panel	2439
CA, additional vapers 18+	Léger Marketing	727
EN, smokers/former smokers 18+	ITC 4C cohort (retention rate 35.7%)	254
EN, smokers/former smokers 18+	Ipsos	3519
EN, additional vapers 18+	Ipsos	551
US, smokers/former smokers aged 25+	ITC 4C cohort	1372
	GfK Knowledge Panel (probability based)	127
	Ipsos	226
US, smokers/former smokers aged 18–24	ITC 4C cohort (retention rate 44.2%)	6
	Lucid (GfK partner panel, opt-in)	496
	Ipsos	12
US, additional vapers 18+	Ipsos	494
Total		12294