Design and validation of a questionnaire to assess the definition process at Van Hiele level 5

Abstract This paper details the process of designing a questionnaire to measure the degree of acquisition of the fifth level of the Van Hiele model in the definition process. The theoretical framework incorporates not only seminal references on this topic but also previous work by the authors, where indicators were developed to characterize this level. Throughout this work, the evolution and development of the questionnaire are presented; in particular, a Delphi methodology with different phases has been followed. The results include the finalized version of a questionnaire that has achieved consensus through expert judgment. This validation process achieved moderate agreement among experts, with a Fleiss’ kappa exceeding 0.60. An essential component of the process involved conducting semi-structured interviews to refine the task design and closed-ended questions, ensuring alignment between the questionnaire items and the indicators that describe the definition processes at Van Hiele level 5. Additional results include a more thorough analysis of the wording and internal structure of the indicators.