To assess the reliability of data collection, interobserver variability was checked at regular intervals.
The other branches (12% of the collection) presented variability in four tests: nitrates reduction, methyl red test, and oxidase and indol production.
However, unless systematic differences were present by site in terms of the severity of illness affecting specimen collection, this variability should have been nondifferential and biased the findings toward the null.
Regardless of whether the sample collected is a first morning void, if the sample does not represent a full 24-hr collection, the variability in urine concentrations (i.e., degree of dilution of the urine components as a result of water intake) must be considered.
Despite being one of the largest cohorts of oral dysplasia used to date in assessing the prognostic ability of biomarkers, there remain the same limitations such as inadequate data collection and variability in the treatment of similar lesions from individuals at different institutions that affect all retrospectively collected cohorts.
However, it is important to standardize the serum sample collection to reduce variability within and between patients [ 18].
Multiple researchers were involved in the data collection and interobserver variability has not been tested; however, all researchers were trained and supervised to obtain these questionnaires correctly.
Paced breathing during the collection of heart rate variability measurements may influence autonomic variables but allowed the confounding effects of respiratory training on the pattern of breathing to be avoided.
Across 13 global clinical studies that utilized the Oragene® OG-300 DNA Self-Collection kit there was variability in the volume of saliva sample collection with ~31% of participants providing 0.5 mL of saliva, rather than the recommended 2 mL.
