Table 3: Calculation of the communalities for each variable using PCA.

VariablesAsthmaticNonasthmatic

Maternal smoking 0.7240.719
In utero smoking0.7250.718
Absence days0.766
Days of continuous absence0.826
Brothers/sisters0.80.792
Birth order0.8450.791
Father education0.8530.788
Mother education0.8170.782
First school performance0.80.784
Final school performance0.890.877
Final grade elementary0.8570.804