Table 3.

Calculation of the communalities for each variable using PCA.

Variables	Asthmatic	Nonasthmatic
Maternal smoking	0.724	0.719
In utero smoking	0.725	0.718
Absence days	0.766
Days of continuous absence	0.826
Brothers/sisters	0.8	0.792
Birth order	0.845	0.791
Father education	0.853	0.788
Mother education	0.817	0.782
First school performance	0.8	0.784
Final school performance	0.89	0.877
Final grade elementary	0.857	0.804