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
From: Influenza epidemics, seasonality, and the effects of cold weather on cardiac mortality
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 |