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Creating a New Difference Variable

Using the New Variable - Difference Function

The NEW VARIABLE - DIFFERENCE function, part of the NEW VARIABLE MENU in EZAnalyze, allows you to create a new variable that contains a new difference score (glossary) quickly and easily - without having to calculate the new scores manually or by writing a formula to add to your Excel data sheet. Difference scores are very useful for showing changes over time with one number.

To create a new difference score variable for your data, select the "New Variable" option from the EZAnalyze menu in Excel, then select "Difference Variable."

In the "New Difference Variable" dialogue box, select one variable (glossary) from the variable list under "Variable 1" and one variable from the variable list under "Variable 2." If you are creating a difference variable that is the difference between a pretest and a posttest, select the variable that represents the posttest from the "Variable 1" list, and the variable that represents the pretest from the "Variable 2" list. The method that EZAnalyze uses for creating the difference score is to subtract "Variable 2" from "Variable 1." If your intervention was effective, subtracting pretest scores from posttest scores should give you positive numbers, which are a little easier to interpret. If you create a new variable and find that most of your numbers are negative, it might be a good idea to switch the variables around so that you are working with positive numbers.

Next, give your new variable a name in the "Variable Name" box. This new name should be a variable name that has not already been used.

When you click OK, a new column will be added to your data sheet that has the name you provided in the "Variable Name" box. The values contained in the cells of the new column will the difference score between the variables you have chosen.

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