Data Normalization

Normalization aims to address the variability in sampling depth and the sparsity of the data to enable more biologically meaningful comparisons. All of these methods require raw count data as input. You can rarefy your data followed by either data scaling or data transformation. However, you cannot apply both data scaling and data transformation, because scaled or transformed data is no longer valid count data.

  • When the library sizes are very different (i.e. > 10 times), rarefying is recommended (see Weiss, S et al.). Rarefying is mainly used for 16S marker gene data and is disabled for shotgun metagenomics data.
  • The normalized data are mainly used for data visualization (boxplot) as well as general statistical methods such as t-tests, ANOVA, etc; For statistical comparisons come with their own normalization methods such as DESeq2, edgeR, limma, or metagenomeSeq, MicrobiomeAnalyst will apply their own normalization methods (as recommended in their user manuals) directly from filtered count data.
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The normalized data will appear in the "Downloads" page named "data_normalized.csv"