1 = male
2 = female

Highest finished education
1 = Lower(no/elementary/secondary lower voc.)geen/basis/MAVO/LBO
2 = Intermediate (secondary medium/high vocational) MBO/HAVO/VWO
3 = Higher (College/University) (HBO/Universiteit)
4 = other education (listed in variable edu_othr)

Country where person was born (only sample 1)
1 = Netherlands
2 = other western country
3 = other non-western country

marital status
1 = married
2 = living together (not married)
3 = single
4 = living with parents

religion (only sample 1)
1 = No religion
2 = Roman Catholic
3 = Reformed
4 = Dutch reformed
5 = Islamitic
6 = other religion (listed in variable reli_oth)

sample 1 or sample 2?
1 = referencegroup general population in norm study
2 = referencegroup general population in MS study

astma, chronic bronchitis or cara during the last 12 months
1 = no
2 = yes

back problems during the last 12 months
1 = nee
2 = ja

healthy versus people with one or more chronic illness
1 = healthy (no chronic illness)
2 = 1 or more chronic illnesses