1. Hamzeh B, Farnia V, Moradinazar M, Pasdar Y, Shakiba E, Najafi F, et al. Pattern of cigarette smoking: intensity, cessation, and age of beginning: evidence from a cohort study in West of Iran. Substance abuse treatment, prevention, and policy. 2020;15(1):1-9.
2. Nketiah-Amponsah E, Afful-Mensah G, Ampaw S. Determinants of cigarette smoking and smoking intensity among adult males in Ghana. BMC public health. 2018;18(1):1-10.
3. Murray CJ, Aravkin AY, Zheng P, Abbafati C, Abbas KM, Abbasi-Kangevari M, et al. Global burden of 87 risk factors in 204 countries and territories, 1990–2019: a systematic analysis for the Global Burden of Disease Study 2019. The Lancet. 2020;396(10258):1223-49.
4. Das SK. Harmful health effects of cigarette smoking. Molecular and cellular biochemistry. 2003;253(1):159-65.
5. Vineis P, Alavanja M, Buffler P, Fontham E, Franceschi S, Gao Y-T, et al. Tobacco and cancer: recent epidemiological evidence. Journal of the National Cancer Institute. 2004;96(2):99-106.
6. Hay S, Collaborators GRF. Global, regional, and national comparative risk assessment of 84 behavioural, environmental and occupational, and metabolic risks or clusters of risks, 1990–2016: a systematic analysis for the Global Burden of Disease Study 2016. The Lancet. 2017;390(10100).
7. Sohrabi M-R, Abbasi-Kangevari M, Kolahi A-A. Current tobacco smoking prevalence among Iranian population: a closer look at the STEPS surveys. Frontiers in Public Health. 2020;8.
8. Okuyemi KS, Ahluwalia JS, Richter KP, Mayo MS, Resnicow K. Differences among African American light, moderate, and heavy smokers. Nicotine & Tobacco Research. 2001;3(1):45-50.
9. Wilson D, Parsons J, Wakefield M. The health-related quality-of-life of never smokers, ex-smokers, and light, moderate, and heavy smokers. Preventive medicine. 1999;29(3):139-44.
10. The W. Curbing the epidemic: governments and the economics of tobacco control. Tobacco control. 1999;8(2):196.
11. Nash SH, Liao LM, Harris TB, Freedman ND. Cigarette smoking and mortality in adults aged 70 years and older: results from the NIH-AARP cohort. American journal of preventive medicine. 2017;52(3):276-83.
12. Breslau N, Fenn N, Peterson EL. Early smoking initiation and nicotine dependence in a cohort of young adults. Drug and alcohol dependence. 1993;33(2):129-37.
13. Fernandez E, Schiaffino A, La Vecchia C, Borràs JM, Nebot M, Saltó E, et al. Age at starting smoking and number of cigarettes smoked in Catalonia, Spain. Preventive Medicine. 1999;28(4):361-6.
14. Morrell HE, Song AV, Halpern-Felsher BL. Earlier age of smoking initiation may not predict heavier cigarette consumption in later adolescence. Prevention Science. 2011;12(3):247-54.
15. Eisner MD, Yelin EH, Katz PP, Shiboski SC, Henke J, Blanc PD. Predictors of cigarette smoking and smoking cessation among adults with asthma. American journal of public health. 2000;90(8):1307.
16. Hastie T, Tibshirani R, Friedman J. The elements of statistical learnin. Cited on. 2009:33.
17. Djalalinia S, Modirian M, Sheidaei A, Yoosefi M, Zokaiee H, Damirchilu B, et al. Protocol design for large–scale cross–sectional studies of surveillance of risk factors of non–communicable diseases in Iran: STEPs 2016. Archives of Iranian medicine. 2017;20(9).
18. Lam E, Giovino GA, Shin M, Lee KA, Rolle I, Asma S. Relationship Between Frequency and Intensity of Cigarette Smoking and TTFC/C Among Students of the GYTS in Select Countries, 2007‐2009. Journal of school health. 2014;84(9):549-58.
19. Wang Q, Shen JJ, Sotero M, Li CA, Hou Z. Income, occupation and education: Are they related to smoking behaviors in China? PloS one. 2018;13(2):e0192571.
20. Hastie T, Tibshirani R. Generalized additive models London chapman and hall. Inc. 1990.
21. Mahmoud HF. Parametric versus Semi and Nonparametric Regression Models. arXiv preprint arXiv:190610221. 2019.
22. Wood SN. Generalized additive models: an introduction with R: CRC press; 2017.
23. Wood S, Wood MS. Package ‘mgcv’. R package version. 2015;1:29.
24. Reidpath DD, Ling M-L, Wellington E, Al-Sadat N, Yasin S. The relationship between age of smoking initiation and current smoking: an analysis of school surveys in three European countries. nicotine & tobacco research. 2013;15(3):729-33.
25. Surveillance. NSAtCDRF, https://www.who.int/ncds/surveillance/steps/afghanistan/ Aoa, en/ (accessed November 5.
26. Surveillance. NSAtCDRF, https://www.who.int/ncds/surveillance/steps/pakistan/ Aoa, en/ (accessed November 5.
27. https:// Q-GATSAoa, November ewinipca, 5.
28. Graham H. Smoking prevalence among women in the European community 1950–1990. Social science & medicine. 1996;43(2):243-54.
29. Rogers EM. Diffusion of innovations: Simon and Schuster; 2010.
30. Ayyagari P. The impact of retirement on smoking behavior. Eastern Economic Journal. 2016;42(2):270-87.
31. Houle B, Siegel M. Smoker-free workplace policies: developing a model of public health consequences of workplace policies barring employment to smokers. Tobacco Control. 2009;18(1):64-9.
32. Villanti AC, Johnson AL, Rath JM. Beyond education and income: identifying novel socioeconomic correlates of cigarette use in US young adults. Preventive medicine. 2017;104:63-70.
33. Itanyi IU, Onwasigwe CN, Ossip D, Uzochukwu BS, McIntosh S, Aguwa EN, et al. Predictors of current tobacco smoking by adolescents in Nigeria: Interaction between school location and socioeconomic status. Tobacco induced diseases. 2020;18.
34. O'Loughlin JL, Dugas EN, O'Loughlin EK, Karp I, Sylvestre M-P. Incidence and determinants of cigarette smoking initiation in young adults. Journal of Adolescent Health. 2014;54(1):26-32. e4.
35. Widome R, Joseph AM, Hammett P, Van Ryn M, Nelson DB, Nyman JA, et al. Associations between smoking behaviors and financial stress among low-income smokers. Preventive medicine reports. 2015;2:911-5.
36. Erbas B, Knudsen TM, Janson C, Nilsen RM, Accordini S, Benediktdottir B, et al. Critical age windows in the impact of lifetime smoking exposure on respiratory symptoms and disease among ever smokers. Environmental research. 2018;164:241-7.