Transforming Data in SPSS
In this guide we will enter some data and then perform a transformation of the data. Transforming data is performed for a whole host of different reasons but one of the most common is to apply a transformation to data that is not normally distributed so that the new, transformed data is normally distributed. Transforming a non-normal distribution into a normal distribution is performed in a number of different ways depending on the original distribution of data but a common technique is to take the log of the data. In this example we will show you how SPSS allows you to do this.
There are an infinite possible ways to tranform data, although there are some approaches that are much more common than others. We will add extra examples of transforming data in the near future.
| Data to Transform |
| 36 |
32 |
45 |
41 |
29 |
22 |
18 |
36 |
10 |
40 |
- Your data should end up looking like the following:
Remember that each individual's results go on a separate line (row) in SPSS.
Published with written permission from SPSS Inc, an IBM Company.
- Rename the variable "Data" instead of the default "VAR00001". You can name it something else if you wish.
- Click on Transform > Compute Variable... in the top menu.
Published with written permission from SPSS Inc, an IBM Company.
- You need to first select the function you would like to use. To do this click "All" in the "Function group:" box then scroll down in the "Functions and Special Variables:" box and click "Lg10" to select it.
Transfer the Lg10 function into the "Numeric Expression:" box by pressing the 
button.
Click the Data variable in the lefthand box and then click the 
button which will result in the expression you see in the "Numeric Expression:" box below.
All to do now is to give this new variable a name. We have called the new variable "TrData". Type this name into the "Target Variable:" box in the top lefthand corner.
Published with written permission from SPSS Inc, an IBM Company.
- Click on the
button.
- You will be presented with the SPSS Data Editor which will now show the log transformed data under the new variable name "TrData" that you defined.
Published with written permission from SPSS Inc, an IBM Company.
