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Twenty-five CEL files (samples) have been imported into PGS (Figure 7)Partek Genomics Suite. Sample information must be added to define the grouping and the goals of the experiment.

• 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 as shown (Figure 8).columns 

• In the Sample Information panel, specify the column labels (Labels 1-4) as Type, Tissue, Subject, and Gender, set each as categorical, and set the other columns as skip (Figure 81). Select OK
  
  

• A dialog window asking if you would like to save the spreadsheet with the new sample attribute will appear. Select Yes
• Make column 5. (Subject) random by right-clicking on the column header and selecting Properties from the pop-up menu (Figure 92). 
  
  

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• Select the Random Effect check box from the Properties dialog (Figure 103) then select OK. 
  
  

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

• To save changes to the spreadsheet, select the Save Active Spreadsheet icon (). Spreadsheets with unsaved changes have an asterisk next to their name in the spreadsheet tree. 

Note: More details on Random vs. Fixed Effects can be found later in this tutorial under the section Identifying Differentially Expressed Genes differentially expressed genes using ANOVA.

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