Table 4.

Model Coefficients for Each Spirometry Parameter, Stratified by Sex

	Intercept ${\beta }_0$	(Age − 45) ${\beta }_1$	(Age − 45)2${\beta }_2$	(Height − 160) (cm) ${\beta }_3$	Model $\sqrt{\text{MSE}}$
FEV1, L
Women
Central American	2.730	−0.0214	−0.0001	0.0289	0.3290
Cuban	2.701
Dominican	2.586
Mexican	2.763
Puerto Rican	2.600
South American	2.781
Other or mixed	2.695
Men
Central American	3.160	−0.0236	−0.00001	0.0422	0.4440
Cuban	3.169
Dominican	2.957
Mexican	3.245
Puerto Rican	3.006
South American	3.277
Other or mixed	3.202
FVC, L
Women
Central American	3.360	−0.0190	−0.0003	0.0382	0.3953
Cuban	3.326
Dominican	3.137
Mexican	3.428
Puerto Rican	3.212
South American	3.450
Other or mixed	3.298
Men
Central American	3.912	−0.0210	−0.0002	0.0552	0.5438
Cuban	3.889
Dominican	3.585
Mexican	4.042
Puerto Rican	3.713
South American	4.093
Other or mixed	3.865
FEV1/FVC ratio, %
Women
Central American	81.344	−0.1858	0.0024	−0.0868	4.3781
Cuban	81.252
Dominican	82.560
Mexican	80.637
Puerto Rican	81.092
South American	80.680
Other or mixed	81.963
Men
Central American	81.203	−0.1476	0.0025	−0.0714	4.9174
Cuban	81.697
Dominican	82.637
Mexican	80.620
Puerto Rican	81.386
South American	80.417
Other or mixed	82.841

Definition of abbreviation: MSE = mean squared error.

Background-specific coefficients ${\beta }_i$ were added to the model intercept ${\beta }_0$ to obtain the intercept for each background.

The intercept is the value at 45 years of age and 160 cm height. The model standard error is the square root of the mean square error. Model coefficients are applied to obtain the predicted value (PV) and lower limit of normal (LLN). For example, FEV₁/FVC ratio (%) for a 65-year-old woman of Central American descent and height of 156 cm is PV =  81.3444 − (0.1858)(20) + (0.0024)(20²) − 0.0868(156 − 160) = 78.9, LLN = 78.9411 − (1.64)(4.3781) = 71.8.