Figure 2.

Path analysis model comprising FEV₁ as continuous variable and clinical signs and symptoms as binary variables. All variables were adjusted for age, sex and BMI, and z-scores (24) were used for FEV₁. Self-attributed allergic rhinitis was excluded from the list of questions since the number of missing values was too high. The model used data for asthma and COPD, which were analyzed in parallel in a two-group design. The arrows indicate directed relationships analogous to linear regression. Only relationships that were statistically significant in at least one of the two groups are shown. The numbers besides the arrows indicate the standardized regression coefficients of the respective arrow, with the upper value referring to COPD and the lower value to asthma. If only value is shown, it refers to asthma, and dotted arrows indicate relationships that were significant only in asthma but not in COPD. As can be seen, this was the case if wheezing was involved. The model was estimated using the generalized least squares method in AMOS; measures of the goodness of fit are given in the text. FEV₁, forced expiratory volume in one second; COPD, chronic obstructive pulmonary disease.