The equity theory: a quantitative perspective using data envelopment analysis Parto Ahmadpour-Samani, Hosein Arman, Amirali Foukerdi, Abdollah Hadi-Vencheh and Reza Kiani Mavi RAIRO-Oper. Res., 56 5 (2022) 3711-3732 Published online: 01 November 2022 DOI: 10.1051/ro/2022178