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. 2022 Mar 9;17(3):e0264394. doi: 10.1371/journal.pone.0264394

Table 1. The socio-demographics and lifestyle covariates selected for this study.

Covariates Coding
Gender 1 = Male
2 = Female
Age Coded as 16–18 and then in 5 years increments (19–23; 24–28; 29–33; 34–38; 39–43; 44–48; 49–53; 54–58; 59–63; 59–63; 64–68; 69–73; 74–78; >78)
Ethnicity 1 = British white
2 = Other white
3 = Indian
4 = Pakistani/Bangladeshi
5 = Black/African/Caribbean
6 = Mixed ethnicities
7 = Other ethnicities
Country of birth 1 = Born in UK
2 = Not born in UK
3 = No answer
Marital status 1 = Married
2 = Living as a couple
3 = Widowed
4 = Divorced/separated
5 = Single never married
6 = No answer
Educational qualification 1 = University degree
2 = High school degree
3 = Lower educational qualifications
4 = Other qualifications
5 = Still a student
Occupation 1 = Managers/Professionals/employers
2 = Non manual workers
3 = Manual workers
4 = Not applicable: Student/retired/Not working
5 = No answer
Perceived financial situation 1 = Living comfortably/doing alright
2 = Living difficultly
3 = No answer
Cigarette smokinga 0 = Non-smoker
1 = Smoker
2 = No answer

Cigarette smokinga: data for cigarette smoking were missing for wave 1 responses and for waves 3 and 4 among individuals aged more than 21 years. Therefore, we replicated the smoking status responses of wave 2 in wave 1 for each individual and in waves 3 and 4 for each individual aged more than 21 years. The smoking status in waves 1, 3, and 4 was coded into “no answer” for individuals who were not present in wave 2.