Main effect age	Comparison <5 vs. 5–10 yrs of age	Comparison 5–10 vs. ≥10 yrs of age	Comparison <5 vs. ≥10 yrs of age	R2 (in %)	Main effect allergy in the family	Main effect frequent infection in the family	Main effect smoking in the house
B
Cough	X	0	0	X	1.6	0	0	0
Blocked nose	X	X	X	0	2.5	X	0	0
Runny nose	X	X	X	0	1.3	0	0	0
Headache	0	0	0	0	0.6	X	0	0
Throat ache	0	0	0	0	1.0	Xc	0	0
Dyspnea	0	0	0	0	–	0	0	0
Ear discharge	0	0	0	0	–	0	0	0
Earache	0	0	0	0	–	0	0	0
Hoarse voice	0	0	0	0	–	0	0	0

(A) Mixed linear regression modeling (LME) on the logit of the proportions of childweeks with “yes, symptom present” analyzed per season. X = significant main effect, 0 = no significant main effect (meaning all symptom frequencies are significantly affected by season, but only runny nose by age and cough by allergy in the family when analyzed separately). Summer/spring/autumn/winter = significant differences in seasonal pattern based on pairwise comparisons using the lsmeans R package. The maximal seasonal difference was found for cough, between 4%, (95% CI 3.1–4.3%) in summer vs. 10% (95% CI 8.9–11.3%) in winter. The maximal age difference was found for blocked nose, between 6% (95% CI 5.2.1–7.6%) <5 years vs. 4% (95% CI 3.4–4.9%) ≥10 years.

^aNo interactions were found, except for cough (more frequent in children with allergy in the family), and for blocked nose and ear discharge (more frequent in children without allergy in the family, but only in the winter).

^bSymptom frequency is in between summer/spring and winter, but the difference is not significant for comparisons with autumn. (B) Linear regression analysis (lm in R) per symptom on the logit of the proportions of childweeks with “yes, symptom present” analyzed year-round (all childweeks together per individual child). X = significant effect (meaning those symptoms were significantly more frequent with lower age or with allergy in the family, except for

^cthroat ache which was significantly more frequent in children without allergy in the family). R² = the percentage of the explained variance. Age analyzed also in pairwise comparisons between the three age groups using the lsmeans R package. Maximal seasonal difference was found for cough: between 4%, (95% CI 3.1–4.3%) in summer vs. 10% (95% CI 8.9–11.3%) in winter. Maximal age difference was found for blocked nose: between 6% (95% CI 5.2.1–7.6%) <5 years vs. 4% (95% CI 3.4–4.9%) ≥10 years. Yrs, years. P < 0.05 were considered significant.