Reliability and Validity
The Gesell Developmental Observation-Revised (GDO-R) Technical Report is a comprehensive evaluation of the reliability and validity of the GDO assessment instrument, updating previously standardized data from 1979. The results of the earlier 1979 study were published in School Readiness; Behavior Tests used at the Gesell Institute. Data presented in the report is based on a sample of assessments administered in of preschool and kindergarten age children between 2008 and 2010 . A GDO Study Reliability and Validity Evidence Executive Summary is also available.
NAEYC accreditation requirements for Standard 4: Assessment of Child Progress
The GDO-R meets National Association for the Education of Young Children requirements to provide a comprehensive assessment tool reflecting on all developmental domains. The Gesell Institute also provides training, as well as mentoring and consulting plans to guide schools and centers in developing an Assessment plan that meets their needs and NAEYC requirements. NAEYC assessment information is available at the NAEYC site here.