Table 1

Key characteristics of data sources

CountryEnglandScotland
Data nameSmoking Drinking Drug Use (SDDU) surveyScottish health survey
Years and interview dates2012: September 2012 – December 2012
2014: September 2014 – December 2014
2016: September 2016 – January 2017
2012: January 2012 – December 2012
2014: January 2014 – February 2015
2016: January 2016 – January 2017
Individuals included2012: 4915
2014: 3483
2016: 6920
2012: 319
2014: 271
2016: 232
Age range11–15 years13–17 years
Exposure to tobacco smoke in cars question2012: Two separate questions: “In the past year, how often were you in your family’s car (OR) someone else’s car with somebody smoking?” (Responses: every day or most days; once or twice a week; once or twice a month; less often than once a month; never in the past year; don’t know)
2014 and 2016: In the past year, how often were you in a car with somebody smoking? This could be your family’s car or someone else’s car. (Responses: every day or most days; once or twice a week; once or twice a month; less often than once a month; never in the past year; don’t know)
In this study ‘every day or most days’ classed as 'regular exposure'
2012–2016: “Are you regularly exposed to other people’s tobacco smoke in any of these places?” (responses: yes/no for in cars/vehicles, etc)
Deprivation marker2012 and 2014: Child reported receipt of free school meals (FSM)2012– 2016: Scottish index of multiple deprivation in five groups
2016:Family Affluence Scale (low, middle, high). Harmonised so low groupe quivalent to receiving FSMHarmonised so most deprived group comparable to receiving FSM or being in lowest affluence band