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• Select Add Sample Attributes in the Import section of the Gene Expression workflow panel
• Choose the option Add Attributes from an Existing Column and select  
• Select OK to open the Sample Information Creation dialog

 In In this tutorial, the file name (e.g., Down Syndrome-Astrocyte-748-Male-1-U133A.CEL) contains the information about a sample and is separated by hyphens (-). Choosing to split the file name by delimiters will separate the categories into different columns 

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• Select the Random Effect check box from the Properties dialog (Figure 3) then select OK. 
  
  

The column 5. (Subject) will now be colored red, indicating that it is a random effect. 

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