Creating a New Standardized (Z) Variable
Using the New Variable - Standardized (Z) Function
The NEW VARIABLE - STANDARDIZED SCORE function, part of the NEW VARIABLE MENU in EZAnalyze, allows you to convert your data to 'standardized scores', or Z scores. Standardizing your variables is useful for putting things 'on the same metric'. For example, if you have two variables, and one is scored on a 5 point scale and the other is scored on a 7 point scale, they are difficult to compare side by side. If you standardize both variables, you can compare the standardized scores side by side easily. You can choose to create standardized scores based on a mean and standard deviation from your own data, or if the population parameters are known, you may choose to use those.
To create a standardized score variable for your data, select the "New Variable" option from the EZAnalyze menu in Excel, then select "Standardized (Z) Score."
In the "Standardize Score" dialogue box, select a variable from the variable list. In the example provided above, you would run this procedure twice - once for the variable on the 5 point scale, and the second time for the variable on the 7 point scale
OPTIONS:
- Use Mean and Standard Deviation from my data - use this option if you want to standardize your scores based on the mean and standard deviation obtained from your sample's data
- Use Mean and Standard Deviation I specify - use this option if you have the 'population parameters' to standardize your sample's data on. Input those parameters into the appropriate spaces provided.
- Create more standardized variables - check this if you have more standardized variables to create. This is simply a time saver.
When you click OK, a new column will be added to your data sheet that has the name "Z_" and the name of the variable you selected to convert into a standardized score.