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Normalization and Low-Value Handling (Optional)

The statistical analyses performed by Cyber-T assumes that the data are approximately normal. This is often not the case with raw microarray (or other high-throughput) data. A common technique is to take the natural log (ln) of the data before processing. However, this approach has several drawbacks, mainly dealing with the inability to handle negative values. An alternative approach called VSN is based on the asinh transform and an assumption of a majority of genes being non-differentially expressed [12]. The webserver allows for pre-processing with optional low value thresholding or offsetting, and optional Log or VSN normalizations. If a Log or VSN normalization is chosen, some plots displaying the effect of the normalization are generated.