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The Sagrada Familia splines
  1. Xavier Basagaña1,2,3
  1. 1Centre for Research in Environmental Epidemiology (CREAL), Barcelona, Spain
  2. 2Universitat Pompeu Fabra (UPF), Barcelona, Spain
  3. 3CIBER Epidemiología y Salud Pública (CIBERESP), Barcelona, Spain
  1. Correspondence to Dr X Basagaña, Centre for Research in Environmental Epidemiology (CREAL), c/Doctor Aiguader 88, Barcelona 08003, Spain; xbasagana{at}

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Sometimes our work goes deep into our brain. A bit like Don Quixote and the windmills, a sick statistical mind looks at Sagrada Familia, Barcelona's iconic church (figure 1), and sees its resemblance to spline basis functions. Then one wonders…would it work? Maybe Gaudí's masterpiece still has some hidden secrets we have yet to unveil. In this paper, basis functions approximating the shape of Sagrada Familia were used to smooth the daily mortality counts in Barcelona during the year 2009, as a fun way to give a flavour on how parametric spline methods work. All this was done with a wisp of hope for serendipitously discovering a revolutionary new statistical tool.

Figure 1

Sagrada Familia church in Barcelona (left panel) and estimated overlaid curves (right panel).


Time series studies of air pollution often use basis functions (eg, natural splines) to smooth the data and adjust for seasonal and temporal trends.1 Splines are actually used to capture non-linear associations in …

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  • Competing interests None declared.

  • Provenance and peer review Commissioned; externally peer reviewed.