Use this text box to specify the value of the Variable Defining the Ratio variable to be used as the denominator for the ratio.
For example, if the above variable is Treatment with values Test and Ref, and you specify Ref here, then the channel of Ref treatment will be used as the denominator of the ratio, whereas the other channel of Test treatment will be used as the numerator of the ratio.
If left blank, the smaller value of the Channel variable is used. For example, if Channel variable is Dye, and has values of Cy3 and Cy5, the default denominator will be Cy3.
For more complex designs where arrays can have different values for the denominator, such as in a loop design, you might want to create a denominator indicator variable using the DATA Step process.
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