Parameter estimated by multiple linear regression analysis models for FEV1/FVC and FEF25–75%/FVC as dependent variables and sex, age class, height, and weight as independent variables.

aThis parameter is set to zero because it is redundant*β coefficients indicate how much a dependent variable changes per each unit variation of the independent variable, taking into account the effect of the other independent variables in the model. For categorical variables, β coefficients represent the effect of moving from the “reference” category (a) to anotherData are shown for 2,393 asymptomatic children.Parameter estimated by multiple linear regression analysis models for FEV1/FVC and FEF25–75%/FVC as dependent variables and sex, age class, height, and weight as independent variables.