The percentage of kids who are "vulnerable," lacking "readiness," "at risk" or whatever they are calling it at the moment is determined by the percentage who fall in the lowest 10th percentile on any one of five "domains" in the questionnaire. That is, those with the lowest 10% of scores in any one of the five areas are labelled "at risk" regardless of their objective standing.

Since this "problem" is based on relative rather than objective "data," it cannot be fixed unless you re-jig the "Instrument."

ESL kids, boys and kids born later in the year more often fall into that category. See pages 11 and 15.

In fact the EDI website at the Offord Centre at McMaster University in Hamilton says, not 25-30%, but ONLY 5% are "vulnerable":

"1 in 20 children enter kindergarten without the skills they need to learn." http://www.offordcentre.com/readiness/

• “Vulnerable are children who score low (below the 10th percentile cut-off of the site/comparison population) in one or more of the five domains.”
  
  
• “Vulnerable are children who score low (below the 10th percentile cut-off of the site/comparison population) on each of the five EDI domains.” (emphasis added)