Table 2 Comparison of participants and non-participants at the first questionnaire round (2004) and responders and non-responders at follow-up 2007/2010 (N=3031)
|  | 2004 | Follow–up 2007 | Follow–up 2010 | |||
|---|---|---|---|---|---|---|
| Â | Participants | Non-participants | Responders | Non-responders | Responders | Non-responders |
| Â | n (%) | n (%) | n (%) | n (%) | n (%) | n (%) |
Gender | ||||||
 Girls | 1520 (50) | 257 (40) | 1164 (54) | 356 (41) | 961 (56) | 559 (42) |
 Boys | 1511 (50) | 393 (60) | 990 (46) | 521 (59) | 753 (44) | 758 (58) |
Variables – 2004 | ||||||
Physical activity | ||||||
Number of weekly hours | ||||||
 None | 63 (2) | n/a | 32 (1) | 31 (3) | 26 (2) | 37 (3) |
 1/2 h | 119 (4) | n/a | 83 (4) | 36 (4) | 59 (3) | 60 (5) |
 1 h | 308 (10) | n/a | 213 (10) | 95 (11) | 174 (10) | 134 (10) |
 2–3 h | 818 (27) | n/a | 564 (26) | 254 (29) | 447 (26) | 371 (28) |
 4–6 h | 1023 (34) | n/a | 752 (35) | 271 (31) | 618 (36) | 405 (31) |
 7 h or more | 700 (23) | n/a | 510 (24) | 190 (22) | 390 (23) | 310 (23) |
Body Mass Indexe | ||||||
 Low (<17) | 270 (9) | n/a | 193 (9) | 77 (9) | 136 (9) | 134 (11) |
 Normal (17/23.29b/23.94c) | 2288 (80) | n/a | 1653 (81) | 635 (78) | 1313 (81) | 975 (78) |
 Overweight (>23.29b/23.94c) | 302 (11) | n/a | 197 (10) | 105 (13) | 165 (10) | 137 (11) |
Mental health (14/15 yr)f | ||||||
 Good | 1947 (65) | n/a | 1394 (66) | 553 (65) | 1132 (67) | 815 (64) |
 Poor | 1030 (35) | n/a | 731 (34) | 299 (35) | 565 (33) | 465 (36) |
Yearly household incomed | ||||||
 Lowest | 889 (29) | 336 (52) | 541 (25) | 348 (40) | 411 (24) | 478 (36) |
 Middle | 1051 (35) | 174 (27) | 767 (36) | 284 (32) | 630 (37) | 421 (32) |
 Highest | 1090 (36) | 138 (21) | 845 (39) | 245 (28) | 673 (39) | 417 (32) |
Highest household educationg | ||||||
 <10 years | 355 (12) | 141 (23) | 204 (10) | 151 (18) | 166 (10) | 189 (15) |
 10–12 years | 1537 (51) | 330 (55) | 1099 (52) | 438 (51) | 867 (51) | 670 (52) |
 13–15 years | 919 (31) | 111 (18) | 688 (32) | 231 (27) | 547 (32) | 372 (29) |
 >15 years | 168 (6) | 21 (4) | 136 (6) | 32 (4) | 121 (7) | 47 (4) |