The case for endobronchial biopsy in the diagnosis of sarcoidosis: Faced with the continuous development of new diagnostic tests, the clinician needs to be able to critically assess their value and their clinical applicability. Using a practical example, the performance of endobronchial biopsy in diagnosing sarcoidosis, this review provides a guide for critically appraising a study evaluating a diagnostic test. The three main steps described are: 1) assessment of the validity of the results based on the scientific methods used; 2) analysis of the results with reference to sensitivity, specificity, predictive value, likelihood ratio, and precision of the diagnostic test in question; 3) determination of whether the results are applicable to an individual patient or to a specific patient population.