Erratum to: Ozone and childhood respiratory disease in three US cities: evaluation of effect measure modification by neighborhood socioeconomic status using a Bayesian hierarchical approach - Cassandra R. O' Lenick; Howard H. Chang; Michael R. Kramer; Andrea Winquist; James A. Mulholland; Mariel D. Friberg; Stefanie Ebelt Sarnat (BMC, 2017)