longitudinal study wave marker
0 = not longitudinal study/case
1 = Wave 1
2 = Wave 2
3 = Wave 3
4 = Wave 4

multiple samples in study
0 = 1 sample
1 = Szalai USA 65 sample
2 = national USA 65 sample
3 = USA 1998-99
4 = USA 2000-01
5 = Slovenia in Szalai Yugoslavia
6 = Serbia in Szalai Yugoslavia
7 = UK 1987 - main sample, drawn from SCELI survey
8 = UK 1987 - spouses and additional household members
9 = East Germany
10 = West Germany
11 = Basque Country in Spain

Household identifier
0 = 1 person sampled per household

-9 = could not be created for study
-7 = not collected for diary group
0 = no
1 = yes