... calculate bias and variance of the estimated pollution effects as function of df. Visual inspection of the boxplots of bootstrapestimates of β as function of the degrees of freedom are informative ... quite expensive for very long time series. Notice also that, because of the availability of a closed form solution of the back-fittingestimate of the smooth part of the GAM model — that isf = ... Journal of the Royal StatisticalSociety Series B, 50, 413–436.Stieb, D., Judek, S., and Burnett, R. (2002). “Meta-analysis of time -series studies of air pollutionand mortality: effects of gases...