Two nurse researchers are interested in studying whether a pain assessment tool for critical care patients is valid and reliable when applied to a group of patients who cannot communicate verbally due to mechanical ventilation. They design a validation study in which randomly selected patients will be assessed using the tool after a painful procedure (tracheal suctioning) and after a nonpainful procedure (oral care). If patient responses result in higher scores after the painful procedure than after the nonpainful one, then the researchers will conclude that the tool is effective for these patients in differentiating pain responses from responses to nursing procedures in general.