nce the ability is a latent trait, it is measured indirectly through observed variables (items). The role of the
questionnaire is crucial for the measurement process, therefore it is important to build adequate items. The validity
of a test can be established through a process of validation and this must be done before the results can be used for
any particular purposes. “Validity is often regarded as involving the question of whether a test measures what it
intends to measure” (Van der Walt & Steyn, 2008, p.192). The aim of this paper is to validate the questionnaire used
in the competition through item response theory approaches (IRT) highlighting the usefulness of this tool in the
exploration of test constructs. In the first phase of this work, some descriptive statistics used in the classical test
theory (CTT) (Kline, 2005) was considered concerning the reliability of each item. These results have suggested to
erasing the most problematic items from the questionnaire. In the second phase, IRT analysis was used to test the
difficulty and discrimination of the remaining items. The data has been analyzed using statistic software R and, in
particular, latent trait models (ltm) package (Rizopoulos, 2006).