“…Early intervention researchers have used Rasch analysis and other IRT procedures to evaluate the psychometric properties of performance checklists (Boavida, Akers, McWilliam, & Jung, 2015), curriculum-based measures (Bricker, Yovanoff, Capt, & Allen, 2003), developmental scales (Chien & Bond, 2009), behavior screening tools for infants (Distefano, Greer, Kamphaus, & Brown, 2014), and individualized family service plan (IFSP) rating scales (Jung, Bradley, Sampson, McWilliam, & Toland, 2015). Snyder and Sheehan (1992) recommended the Rasch approach in education and psychology because it assumes invariant, unidimensional linear measurement, meaning it does not assume that all items are equally "difficult.…”