How was the EDI developed?
The EDI was developed by Drs. Dan Offord and Magdalena Janus in response to a need for a uniform methodology that would assess children's level of development in their first year of schooling. Initiated in the North York community of Ontario in 1999/2000, the EDI has since been implemented throughout Ontario, Manitoba, Saskatchewan, and the Yukon as well as parts of Nova Scotia and Alberta. It has also been implemented in a number of countries around the world.
In 1999, under the leadership of Dr. Clyde Hertzman , HELP launched the Early Child Development Mapping Project in British Columbia; the project that initiated EDI collection in British Columbia. British Columbia is the first jurisdiction to track the development of its entire population of kindergarten children. This process has been completed multiple times in each area of the province, revealing the population-level trends in children's development in neighbourhoods throughout B.C.
The EDI provides population-based data about early child development to communities and governments so that they can put into place programs and policies to support healthy child development in all families. Illustrating with data the disparities in children's development inspires action to redress these inequities.
The EDI has been studied by national and international researchers in a continued effort to assess its psychometric reliability and validity. Furthermore, HELP and its international partners are engaged in an ongoing validation research program to evaluate whether the EDI accomplishes its purposes. To date, over 30 studies investigating aspects of the EDI's reliability and validity have been published in the peer-reviewed literature, including two special issues on the EDI (Guhn, Janus, & Hertzman, 2007; Guhn, Zumbo, Janus, & Hertzman, 2011).
These studies examined topics such as the EDI's psychometric reliability (Janus & Offrod, 2007; Brinkamn et al.), item bias (Guhn, Gadermann, & Zumbo, 2007), convergent and discriminant validity (Hymel, LeMare, & McKee), concurrent validity (Lesaux, Vukovic, Hertzman, & Siegel, 2007) predictive validity (Dubois et al., 2007, Lloyd & Hertzman, 2009), and multilevel validity (Forer & Zumbo, 2011), as well as the theoretical, philosophical, and methodological foundations of the EDI (Guhn, Zumbo, Janus, Hertzman, 2011; Guhn & Goelman, 2011; Hubley & Zumbo, 2011; Janus & Offord, 2007; Sam, 2011).