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Principal Components Analysis (PCA) is an excellent method to visualize similarities and differences between the samples in a data set. PCA can be invoked through a workflow, by selecting () from the main command bar, or by selecting Scatter Plot from the View section of the main toolbar. We will use a workflow. 

  • Select Gene Expression from Select Gene Expression from the Workflows drop-down menu
  • Select PCA Scatter Plot from the QA/QC section of the Gene Expression workflow

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Numbered figure captions
SubtitleTextPCA scatter plot showing treatment, batch, and time information for each sample. A batch effect is clearly visible.
AnchorNameConfigured PCA scatter plot

PCA is particularly useful for identifying outliers and batch effects in data sets. We can see a significant batch effect in this dataset as samples cluster separate by batch. To make this more clear, we can add an ellipses by Batch. 

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Numbered figure captions
SubtitleTextEllipses around batch groups show that samples separate by batch
AnchorNamePCA plot with ellipses

Two ways Ways to address the batch effect in the data set will be detailed later in this tutorial. 

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