“…Briefly, the sequence of development of each infant-toddler IGDI has proceeded as follows: (a) Building out a prototype measure using CTT and testing proof of concept and pilot psychometrics in a small sample of children with the assessments administered by research staff (Carta et al, 2004; Greenwood et al, 2002; Greenwood, Walker, et al, 2006; Luze et al, 2001); (b) improving the measure based on these results and refinement of protocols (Greenwood, Carta, et al, 2006; Greenwood et al, 2013); (c) development of web tools that support program staff efforts to be certified assessors, coders who score performance, and reporters and users of the results with caregivers (Buzhardt et al, 2011, 2022); (d) testing use of the IGDI in a larger number of programs and children supported by website tools for program, and data management (Greenwood et al, 2010, 2018, 2020), (e) testing sensitivity to intervention effects (Buzhardt et al, 2018, 2020), and (f) psychometric studies including invariance test in large, time-displaced samples (Greenwood et al, 2013, 2020).…”