A practical example of calculating Cronbach's alpha as a tool for measuring the internal consistency of questionnaire items of a qualitative nature

In the domain of sports sciences, questionnaire-based measurement represents a fundamental methodological approach for gathering relevant data. Such data may be either quantitative or qualitative in nature. In the case of qualitative variables, questionnaires are frequently employed to assess psychological, social, and behavioral characteristics of athletes. However, the outcomes of these measurements are often subject to respondents' subjective perception as well as temporal fluctuations in behavior, which may compromise the objectivity of the results. When developing a new questionnaire intended to capture qualitative constructs, it is essential to evaluate its psychometric properties, with particular emphasis on its measurement quality. One of the key indicators of quality is reliability, defined as the degree of stability and internal consistency of the instrument over time. This study presents one of the most used approaches for assessing internal consistency—Cronbach’s alpha coefficient—as a tool for estimating the reliability of questionnaire-based instruments in sport psychology research.