About Me

Dr. Weiss was Vice President of Global Research and Development for Pearson Clinical Assessment, publisher of the Wechsler scales, where he worked for 27 years before retiring in 2018. He oversaw a department of 200 professionals in 13 countries spanning 4 continents. He remains active in the profession as a consultant, speaker, writer, editorial board member, and expert witness.

Dr. Weiss bore full responsibility for all scientific research and test development activities related to Pearson's large suite of clinical assessment instruments around the globe including such widely used tests as the WAIS, WISC, Vineland, ABAS, WMS, RBANS, MCMI, Kaufman, DAS, NEPSY, D-KEFS, BDI, NNAT, Ravens, WIAT, and dozens of others. He is able to speak with inside knowledge about psychometric and best practice issues related to all Pearson assessments.

His unique value as an expert witness is that for more than a quarter century he held ultimate responsibility for the development of all current and several previous editions of the Wechsler scales of intelligence (i.e., WAIS-III, WAIS-IV, WISC-III, WISC-IV, and WISC-V), and thus opines authoritatively about these instruments. His responsibilities included final authority over all aspects of each revision including the test questions and structure, research and development, creation of the scoring rules and norms, writing of the technical, administration and scoring manuals. He also oversaw the collection of tens of thousands of subjects used in the research and development phases and is therefore uniquely qualified to determine if a Wechsler protocol was administered and scored validly, and what types of breaks in standardized procedures do and don't threaten the validity of the score - including the presence of third parties or video cameras in the examination room.

Further, he is considered an expert on the Flynn effect, having written influential articles on the subject, and serving as a co-editor of a special issue of a journal devoted to the topic.

Widely acknowledged as one of the most experienced psychological test developers in the world, Dr. Weiss has overseen the development of hundreds of Pearson tests in the areas of cognition, neuropsychology, memory, personality, adaptive functioning, achievement, and personnel selection. Thus, his experience in applied psychometrics is deep and broad. He is very well qualified to judge the psychometric adequacy of any psychological test for use in high stakes evaluations. Further, he is able to explain in common language the foundational principles of applied psychological measurement such as reliability, standard error of measurement, test norm development, differences between types of scores (raw, percentile rank, scaled scores, etc.), different types of validity, practice effects, why tests are renormed, and why scores may differ between tests measuring the same construct