Reviews the GISTIC (Genomic Identification of Significant Targets in Cancer) method developed at the Broad Institute by Beroukhim et. al. [Assessing the significance of chromosomal aberrations in cancer: Methodology and application to glioma] and how to use it within Nexus Copy Number. This method identifies regions that are significantly gained or lost across a set of samples, giving a greater weight to high-amplitude events which are less likely to represent random aberrations.