“…The returns to scale of the inverse DEA models in this paper is from the base DEA models. Following the inverse DEA models for estimating merger gains in the literature (Amin & Al‐Muharrami, 2018; Amin, Al‐Muharrami, & Toloo, 2019; Amin, Emrouznejad, & Gattoufi, 2017a, 2017b; Gattoufi, Amin, & Emrouznejad, 2014), the above inverse DEA models developed in this paper assumed variable returns to scale. The type of returns to scale can be changed to other appropriate forms of returns to scale depending on the application.…”