Table 1.

Covariates included additionally to smooth Functions of Temperature, relative Humidity and Air Pressure, and 6 Terms for Weekday in Quasi-Poisson Regression Models 1 to 5, and total Degrees of Freedom

Model	Effective degrees of freedom	Degrees of freedom of smooth function of time	Smooth function of influenza admissions, mean of lags 0–4, df = 4	Sinusoidal function of time with period of 1 year
Main analyses
1	60	5 per year (45)
2	31	10	x	x
Sensitivity Analyses
1’	64	5 per year (45)	x
2’	27	10		x