Country or region of survey
1 = Argentina
2 = Austria
3 = Australia
4 = Belgium
5 = Brazil
6 = Bulgaria
7 = Canada
8 = China
9 = Denmark
10 = Estonia
11 = Finland
12 = France
13 = Germany
14 = Hungary
15 = India
16 = Ireland
17 = Israel
18 = Italy
19 = Japan
20 = Latvia
21 = Lithuania
22 = Netherlands
23 = New Zealand
24 = Norway
25 = Peru
26 = Poland
27 = Portugal
28 = Republic of Korea
29 = Romania
30 = Russia
31 = Slovak Republic/Czechoslovakia
32 = Slovenia/Yugoslavia
33 = South Africa
34 = Spain
35 = Sweden
36 = Turkey
37 = United Kingdom
38 = USA

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 = original NHAPS
4 = 95 NHAPS supplement
5 = USA 85 mail back sample
6 = USA 85 phone interview
7 = USA 85 personal interview
8 = Szalai Slovenia
9 = Szalai Serbia
10 = West Germany
11 = East Germany

Household identifier
0 = 1 person sampled per household

Region of residence
1 = Amsterdam, Rotterdam, & den Haag
2 = Drenthe
3 = Flevoland
4 = Friesland
5 = Gelderland en Zop
6 = Groningen
7 = Limburg
8 = Noord Brabant
9 = Noord Holland Zonder 1
10 = Overijssel en Nop
11 = Utrecht
12 = Zeeland
13 = Zuid Holland Zonder 1

-9 = could not be created for study