Sample

Natsal-3 used a stratified, clustered sample with postcode sectors as the Primary Sampling Units (PSUs). The sampling frame was the Postcode Address File. PSUs were stratified by geographical region (Standard Statistical Region), population density, proportion of the population under 60 and proportion of households with a head of household in a non-manual occupation. PSUs were systematically selected with probability of selection proportionate to population size.

Within each selected PSU, 30 addresses were systematically selected. After wave 2 of fieldwork this increased to 36 as a higher proportion of addresses were being screened out as ineligible than originally anticipated. A total of around 59,000 addresses were selected. One resident within the age range was randomly selected and invited to participate at each address where contact was made.

Because of the policy focus on young people, the decision was taken to boost the proportion of younger people aged 16-34 years, so that they would constitute approximately half the overall sample.

The target age distribution of the sample was:

 

16-19

20-24

25-29

30-34

35-39

40-44

45-49

50-54

55-59

60-64

65-69

70-74

Total

Initial

434

529

752

920

1076

1028

913

838

1010

892

818

789

10,000

Boost

1383

1195

1435

987

-

-

-

-

-

-

-

-

5,000

Total

1817

1724

2187

1907

1076

1028

913

838

1010

892

818

789

15,000