 This is one of the reasons for their popularity in applications.Other methods in this class include the 2- and 3-alternative forced choice methods, the triangular method which is a special case of Richardson's method, the duo-trio method and the specified and unspecified methods of tetrads.All of these methods have well developed Thurstonian scaling models as discussed recently in Ennis (2016) which also includes a Thurstonian model for first-last or most-least choice and ranks with rank-induced dependencies.