Analysis of test results and test quality during certification of non-destructive testing specialists

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This article analyzes the results of personal certification for eddy current testing of railway facilities. The influences of education level, the work experience, the candidate age on the qualifying examinations results are considered. The conformity between test task difficulties and certification candidate training is analyzed with Rasch method. The characteristic curves of test task difficulties and the characteristic curves of candidate training levels are constructed. The results general and special examinations of 2020 and 2021 are analyzed to identify extreme test questions. The research results enable to assess the candidate training and the test task difficulties through latent parameters measured as logit unit. The analysis identified test tasks with overstated and understated task difficulty logits compared with the logits of the candidate training, assessed the correspondence between test difficulties and training candidate level, and assessed a distribution uniformity of the tasks’ difficulty. The required training logit of candidates for the certification is calculated for successful passing general and special exam tests. The getting results give a basis for further analysis of the tasks complexity, identification the reasons for the insufficiency of the auditory material familiarization for the tasks with low rate of response, for making adjustments to the consulting sessions, as well as the content and form of the test.