Heesun Chang is an Assistant Professor of Bilingual/ESL Education in the Department of Educational Psychology at Texas A&M University. He obtained his Ph.D. in Language and Literacy Education at the University of Georgia. With his interdisciplinary expertise in applied linguistics, educational measurement, and statistics, he is interested in analyzing language and discourse patterns and features through corpus and statistical methods to inform language and literacy education and assessment. He is also interested in validating/evaluating the psychometric properties of assessment/survey instruments. His recent research focuses on analyzing the linguistic features of international teaching assistants (ITAs) to explore, investigate, and evaluate the validity issues in ITA training and assessment.