Null SNP Variables

Use this field to specify the marker variables to use as null SNPs when calculating the variance inflation factor for genomic control, which is a method for removing the effects of population stratification from the test statistics. They are used only when the Apply VIF for genomic control check box on the Options tab is selected. When the Apply VIF option is checked and no variables are selected here, all marker variables are used as null SNP variables, by default.

To Specify One or More Null SNP Variables:

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Specify the Input SAS Data Set.

All of the variables in the specified data set are displayed in the Available Variables field.

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Examine the list of available variables.

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Left-click a single variable, or hold down Ctrl while left-clicking to select multiple variables.

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Click to add the highlighted variable(s) to the Null SNP Variables field.