Table 1.
Comparison between previous population studies in Östhammar, Sweden. Age, sex and education level at different stages of the sampling process. From the first population sample in 1988 to the present study 1996. ns = p > 0.05.
| Group (G) | Sample | Year | n | Age years mean (SD) | Sex % males | Education median level (range) |
| 1 | First population sample | 1988 | 1156 | 48.9 (16.0) | 50.4 | 3 (1–4)* |
| 2 | Eligible sample | 1995 | 1428 | 49.9 (17.2) | 49.9 | 3 (1–4)** |
| 3 | Population sample | 1995 | 911 | 49.2 (16.46) | 47.0 | 3 (1–4) |
| 4 | Sample group FGID | 1995 | 244 | 45.5 (15.3) | 36.1 | 3 (2–4) |
| 5 | Sample Group SSF | 1995 | 219 | 51.7 (17.6) | 51.6 | 3 (1–4) |
| 6 | Study Group FGID | 1996 | 141 | 45.7 (14.3) | 34.0 | 3 (2–4) |
| 7 | Study Group SSF | 1996 | 97 | 52.4 (15.3) | 48.0 | 3 (1–4) |
| G2 vs G3 | ns | ns | ||||
| G2 vs G3 | ns | ns | ns | |||
| G4 vs G6 | ns | ns | ns | |||
| G5 vs G7 | ns | ns | ns |
*responders = 1156 **responders n = 1384