Multi-Dimensional Scaling (MDS) plots comprise a means of visualizing the level of similarity of individual cases of a dataset. MDS uses absolute distance metrics such as the classical Euclidean distance as a similarity measure. MDS serves as a quality control and it can be interpreted as follows: when the distance among samples of the same biological condition in the MDS space is small, this is an indication of high correlation and reproducibility among them. When this distance is larger, this constitutes an indication of low correlation and reproducibility among samples. It can help to identify mislabled samples or to exclude poor samples from further analysis.