Darrell Hull received his PhD in Educational Psychology from Baylor University. He has been involved in STEM and STEM education for more than 20 years, as principal investigator for several NSF and U.S. Department of Education programs. During the last 10 years he has conducted research on positive youth development in the Caribbean, working in the Bahamas, Trinidad and Tobago, Jamaica, and Belize were he has directed randomized trial studies and quasi-experimental trials focused on adolescents. Based on his work with Item Response Theory and Generalizability Theory, Dr. Hull teaches measurement in the Educational Research PhD program and is a frequent psychometric consultant to assessment organizations in the DFW area.