Main characteristics of the different reference equations
| First author and year | Normal selection criteria | Age range yrs | Sex | Body size range# | Equipment |
| Brändli 1996 8 | Random selected sample from Switzerland | 18–60 | 1890 females; 1267 males | Females (height 163±6 cm, weight 62±11 kg); males (height 176±7 cm, weight 75±10 kg) | Pneumotachographs |
| Crapo 1981 3 | Selected volunteers members of the Church of Jesus Christ of Latter-Day Saints | 15–84 | 125 females; 126 males | Females (height 161±7 cm, weight 68±13 kg); males (height 175±7 cm, weight 78±13 kg) | Water-sealed 13.5 L metal bell spirometer |
| ECSC 1993 4 | Summary equations obtained from different studies | 18–70 | Females (height 145–180 cm); males (height 155–195 cm) | ||
| Enright 1993 14 | Randomly selected sample from the general population | 65–85 | 532 females; 245 males | Females (height 159±6 cm, weight 72±9 kg); males (height 172±7 cm, weight 77±10 kg) | Water-sealed spirometer |
| Hankinson 1999 6 | Stratified multistage probability sample of the USA population | 8–80 | 1383 females; 898 males | NP | Dry rolling-seal spirometer |
| Knudson 1983 2 | Randomly selected sample from the general population of the area | 20–88 (females); 20–85 (males) | 204 females; 86 males | NP | Pneumotachograph |
| Langhammer 2001 9 | Randomly selected sample from the Nord-Trondelag Health Study | 20–80 | 546 females; 362 males | NP | Pneumotachographs |
| McDonnell 1998 15 | Cohort of the Adventist Health Air Pollution study | 43–79 | 366 females; 199 males | Females (height 162±7 cm); males (height 176±7 cm) | Rolling seal spirometers |
| Paoletti 1986 7 | Randomly selected sample from the general population of the area | 21–64 (females); 29–64 (males) | 313 females; 59 males | Females (height 157±6 cm); males: NP | Fleish no. 3 pneumotach HP47804 System |
| Roca 1986 5 | Selected volunteers | 20–70 | 427 females; 443 males | Females (height 158±4 cm, weight 60±9 kg); males (height 170±7 cm, weight 71±8 kg) | Fleish no. 3 pneumotach HP47804 HP Vertek System |
| Sharp 1996 13 | Survivors of population-based longitudinal study | 71–90 | 528 males | Height: 162±5.7 cm; weight: 61.2±7.6 kg | Water-sealed spirometer |
ECSC: European Community for Coal and Steel
NP: not provided
#: data are presented as mean±sd and ranges