Table 3.

Application of algorithmic transformations across cohorts

Variable	Transformation	Cohort
		Airwave	ELSA	Generation Scotland	Memento
Smoking	Never	Never	Ever smoked Yes/no	Never	Never
	Ex	Ex	–	Ex	Ex
	current	current	–	current	current
Smoking?	Yes
	no
Ethnicity	White	White	White	White	–
	Black	Other	Non white	–	–
	Asian	-	–	Asian	–
	Mixed	-	–	Mixed	–
Education	Post grad equivalent (ISCED 7/8)*	Post grad	–	–	Higher dipl
	Degree equivalent (ISCED 4–6)	Deg. equiv	Deg. Equiv	College/Uni	Degree
	Secondary (ISCED 2/3)	–	Higher ed	–	General Bac
		A level NVQ3	NVQ3	Highers	Tech Bac
		GCSE NVQ2	NVQ2	Standards	CAP/BEP
		NVQ1	NVQ1	CSE equivalent	Elementary
		–	Foreign/other	–
	<  = Primary (ISCED 1)	–	–	Certificate	Primary
		No qualification	No qualification	No qualification	No qualification
Cohabitation	Single	Single	Single	Are you living as a couple? yes/no	Single
	Married/cohabiting	Married	Married	–	Married/cohabiting
		–	Remarried	–	–
		cohabiting	–	–	–
	Divorced/separated	Divorced	Divorced	–	Divorced/separated
		Separated	Separated	–	–
	widowed	–	Widowed	–	Widowed
	Other	Other	–	–	–
Housing type	House/bungalow	–	–	House/bungalow	Single family dwelling
	Apartment	–	–	Apartment/flat	Apartment
	Sheltered/residential	–	–	Hostel	Residential
		–	–	Mobile/caravan	Sheltered
		–	–	Sheltered	Religious community
		–	–	Homeless	Care home
	Other	–	–	Other	Other
Household income	Four quantiles using local currency	Annual: < £25,999, 26,000–37,999, 38,000–59,999, 600,000 +	Gross monthly and annual in Pounds Sterling	–	Monthly: €400– < 800 800– < 1200 1200– < 1800 1800– < 2500 2500 < 4000 4000– < 6000 6000 +
Vigorous exercise	Yes/No	–	Do you attend sports clubs, gym, exercise classes?	–	Days per week Hours per day Minutes per day No vigorous exercise
Moderate exercise	Yes/No	–	–	–	Days per week Hours per day Minutes per day No moderate exercise
Walking	Yes/No	–	–	–	Days per week Hours per day Minutes per day No walking

^*ISCED International standard classification of education [28]