Table 3. Reference equations of commonly applied IOS indices for men.

Equations				Coefficients of
Percentile		Quantile value	Intercept	Age	Height	Weight
Z5 (kPa s L−1)	5%	0.18	1.2018022	−0.0025997	−0.0048804
	50%	0.28	1.0719341	−0.0001490	−0.0059151	0.0029873
	95%	0.47	0.6514286	0.0035450	−0.0026455
R5 (kPa s L−1)	5%	0.17	1.0685571	−0.0022403	−0.0043124
	50%	0.26	0.9861137	−0.0001223	−0.0055278	0.0029891
	95%	0.44	0.6683472	0.0029051	−0.0026280
R20 (kPa s L−1)	5%	0.13	0.6342369	−0.0019656	−0.0021069
	50%	0.20	0.7722257	−0.0006446	−0.0037120	0.0013924
	95%	0.32	1.1824320	−0.0003590	−0.0048639
R5–R20 (kPa s L−1)	5%	0.02	0.0358593	0.0003691	−0.0002018
	50%	0.06	0.3140859	0.0004753	−0.0024277	0.0016455
	95%	0.13	0.0705078	0.0014497	−0.0002216
(R5–R20)/R20*100 (%)	5%	11.57	37.8410856	0.2236991	−0.2295525
	50%	29.92	31.9858256	0.4017027	−0.4662949	0.6370333
	95%	61.12	−2.6268375	0.4546831	0.1793720
X5 (kPa s L−1)	5%	−0.15	−0.5568254	−0.0004762	0.0025397
	50%	−0.09	−0.4670275	−0.0003344	0.0027755	−0.0010424
	95%	−0.04	−0.2058333	0.0006944	0.0006944
AX (Hz kPa s L−1)	5%	0.07	0.0430162	0.0012195	−0.0002327
	50%	0.26	1.7584772	0.0027451	−0.0132469	0.0077552
	95%	0.83	2.2955939	0.0161916	−0.0139157
Fres (Hz)	5%	8.48	26.6835318	0.0582454	−0.1720116	0.1003766
	50%	13.35	24.9095582	0.1031097	−0.1874266	0.1675556
	95%	18.53	10.1428126	0.1772368	−0.0120106

Equations are derived from lung healthy men aged 45 to 89 years. Quantile regression equations for median, 5th and 95th percentile with age in years, height in cm and weight in kg (e.g., Z5–50% = 1.0719341–0.0001490 age–0.0059151 height +0.0029873 weight).