ABSTRACT
This chapter introduces the test equating methods without using item response theory. It demonstrates examples using different designs and functions using the equate package in R. Equating adjusts for the variation in difficulty of the test forms and allows the scores on the various test forms to be interchangeable and more comparable. Different equating designs can be employed in an equating study and the decision of which design to use has important statistical implications. To follow the convention used in the equate package it categorizes equating designs as either a single group, equivalent groups, or nonequivalent groups. The equating functions in the equate package fall into two broad categories: linear and nonlinear functions. Identity and mean functions are all restricted variants of the linear function. Two nonlinear equating functions are available for equate: equipercentile and circle-arc functions. The nonlinear functions include equipercentile, circle-arc, and composite functions. Identity and mean functions are all restricted variants of the linear function.
