Short note explaining the error in ‘Machado M.A.G. and Costa A.F.B. (2014) “A side-sensitive synthetic chart combined with an X chart.” International Journal of Production Research 52 (11): 3404–3416’

National Research Foundation [Thuthuka Program: TTK14061168807; grant number 941]; National Research Foundation and Department of Science and Technology [Innovation Doctoral Scholarship SFH14081591713].