The problem of aneuploidy (or hyper-ploidy) often comes from samples with a lot of gains or losses and those not showing any probes at the zero (diploid) line. Such a case may or may not have the correct settings and typically, due to a lack of re-centering (normalization), no part of the genome is centered at the zero line. Normalization is necessary in all array data to balance the strength above the zero line with that below it. The video will go over different ways to re-center (median, mode, median probe intensity of known diploid regions) and in what scenarios (e.g. aCGH arrays, SNP arrays) to use a specific re-centering method.