Polytomous Limited is an independent consultancy specialising in psychometrics, assessment design, evaluation, and standard setting. The company supports organisations across education, language testing, and professional certification by providing rigorous, evidence-based solutions grounded in internationally recognised standards of good practice. Polytomous Limited has particular expertise in the design and delivery of standard setting studies, with its core team holding doctoral-level research backgrounds focused specifically on standard setting theory and practice. Its work covers methods such as Angoff, Item Descriptor Matching method, Bookmark, Body of Work, and related judgment-based and model-based approaches, alongside Rasch and IRT analysis, validation and alignment studies, and technical capacity building. Across all projects, Polytomous emphasises defensible cut-score decisions, transparency of judgemental processes, and the integration of academic rigour with operationally sustainable assessment systems.
Dr Charalambos (Harry) Kollias is Director and Founder of Polytomous Ltd, a specialist consultancy in psychometrics, assessment, and evaluation. He holds a PhD in Language Testing from Lancaster University and has over thirty years of experience in educational measurement and language assessment, with a particular focus on standard setting, psychometric analysis, and international framework alignment.
Dr Kollias is internationally recognised for his expertise in conducting and evaluating standard setting and benchmarking workshops, including in virtual, face-to-face, and hybrid formats. He has led alignment studies using Policy Linking methodologies to map assessments to frameworks such as the Common European Framework of Reference for Languages (CEFR), the European Qualifications Framework (EQF), and the Global Proficiency Framework (GPF), supporting global education policy and SDG 4.1.1.1 reporting. He is the author of Virtual Standard Setting: Setting Cut Scores (Peter Lang, 2023), a comprehensive guide to remote standard setting methodologies and psychometric considerations. His psychometric work includes test equating through anchor tests and common items, calibration using Rasch and Item Response Theory, DIF analysis, and validation of both cognitive and non-cognitive instruments across diverse testing contexts.
Dr Kollias is committed to strengthening assessment systems through psychometric capacity building. He has developed and delivered targeted training in Rasch and Item Response Theory (IRT), test equating, DIF analysis, and instrument validation. His work includes mentoring practitioners in the design, calibration, and evaluation of assessments, as well as in the interpretation and application of psychometric evidence. Through tailored workshops, technical consultations, and resource development, he supports the development of sustainable, locally owned psychometric expertise that underpins valid and reliable assessment practices.