Table 2 Selected characteristics of nationally representative studies* of cessation attempts among adolescent smokers according to type of cessation attempt estimate.

Characteristic	Number of estimates
	Any cessation attempt			Multiple cessation attempts
	6‐month prevalence	12‐month prevalence†	Lifetime prevalence	12‐month prevalence‡	Lifetime prevalence	Duration of cessation attempt
Geographic location
North America	330,37,70,74,75	102,33,35,36,50,51,62,63,64,65,66,67	62,37,70,74,75	562,63,64,65,66	27,74	337,70,74
Central America and the Caribbean	0	933,41,47,48,49,71,72,73	0	0	0	0
South America	0	233,42	0	0	0	0
Europe	0	444,45,46,53	132	0	0	0
Africa	0	739,40,52,57,58,59,60	0	0	0	0
Middle East	0	533,54,55,56	0	0	0	0
Asia	0	533,38,43,61	0	0	0	0
Oceania	0	233	168	0	168	0
Year of data collection
Prior to 1980	0	0	12	0	0	0
1980–1989	130,74,75	0	32,74,75	0	174	174
1990–1999	137	102,33,35,39,42,63,72	232,37	163	137	137
2000–2005	170	3433,36,38,40,41,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,64,65,66,67,71,73	268,70	462,64,65,66	168	170
Sampling frame
Schools	0	3833,35,36,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,71,72,73	52,32,68	0	168	0
Households	130,74,75	62,62,63,64,65,66,67	174,75	562,63,64,65,66	174	174
Other§	237,70	0	237,70	0	137	237,70
Sample size||
Not stated	0	22,63	0	163	0	0
<500	170	2333,40,41,42,47,48,49,52,54,55,56,57,59,60,61,71,73	268,70	0	168	170
500–<1000	0	833,46,62,64,65,66,67,72	0	462,64,65,66	0	0
⩾1000	230,37,74,75	1135,36,38,39,43,44,45,50,51,53,58	62,32,37,74,75	0	237,74	237,74

*We defined a study as a sample of individuals in a particular place during a particular time period.

†Although in some instances these were available from other reports,³¹,⁷¹ study characteristics were abstracted from The Global Youth Tobacco Survey Collaborative Group³³ for the following study populations: Barbados (1999), Fiji (1999), Gaza Strip (2001), Jordan (1999), Montserrat (2000), Northern Mariana Islands (2000), Singapore (2000), Sri Lanka (1999), and St. Vincent and the Grenadines (2001). Study characteristics for Bahamas (2000) were abstracted from Perez Martin and Peruga (2002).⁷¹

‡Study characteristics for Canada (2000) were abstracted from Health Canada.⁶⁶

§Other includes studies with a sampling frame that included both schools and households.³⁷,⁷⁰

||Reflects the sample size of current smokers. The sample size for age and smoking history specific subgroups as well as for the duration of cessation attempts was usually smaller. If the sample size of current smokers was not provided, wherever possible, it was estimated from (a) the total study sample size multiplied by the proportion of current smokers or (b) the large‐sample 95% confidence interval for a population proportion (p±1.96*SE_p) where p  =  prevalence and SE_p  =  standard error of p.