title: Erratum to: Exploring functional data analysis and wavelet principal component analysis on ecstasy (MDMA) wastewater data.
authors.affiliation: Norwegian Centre for Addiction Research, University of Oslo, Oslo, Norway. stefania.salvatore@medisin.uio.no.
authors.forename: Stefania
authors.initials: S
authors.lastname: Salvatore
authors.affiliation: Norwegian Centre for Addiction Research, University of Oslo, Oslo, Norway.
authors.forename: Jørgen G
authors.initials: JG
authors.lastname: Bramness
authors.affiliation: Norwegian Centre for Addiction Research, University of Oslo, Oslo, Norway.|Oslo Centre for Biostatistics and Epidemiology, Institute of Basic Medical Sciences, Oslo, Norway.
authors.forename: Jo
authors.initials: J
authors.lastname: Røislien