Which of the following may lead to reproducibility issues in research?

Omission of materials and procedures can significantly lead to reproducibility issues in research. When researchers fail to provide complete details about the materials used or the steps taken in their methodologies, it creates barriers for other scientists attempting to replicate the experiment. Without this information, other researchers may not be able to accurately recreate the study, leading to variations in results that could stem from differences in the materials or processes applied. This lack of transparency can undermine the credibility of the findings and hinder the advancement of knowledge in the field, given that reproducibility is a cornerstone of scientific inquiry. Providing a comprehensive account of methods and materials is crucial for ensuring that other researchers can follow the same steps and verify the results.