The fallacy of small sample size - Comment on: Geier D.A., Kern J.K., Homme K.G., Geier M.R., 2018. The risk of neurodevelopmental disorders following thimerosal-containing Hib vaccine in comparison to thimerosal-free Hib vaccine administered from 1995 to 1999 in the United States. Int. J. Hyg. Environ. Health. 221: 677–683