How to Convert Continuous Variables into Categorical in SPSS

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Testing the causal model in AMOS may involve having moderator variables that are categorical. This can be done through Multi-group analysis. In cases where available data are continuous (e.g. age, years of experience, etc.), conducting Multi-group analysis is also possible. However, you need to convert first these variables into categorical ones, for them to be used in AMOS. 


For this example:

Age is our continuous variable. We will code high and low values of age.


The steps would involve A) Computing for the mean score, and B) Recoding into a different variable. The following sections show the step-by-step process.

A. Compute for the Mean Score
  1. Go to 'Analyze' -- Descriptive Statistics -- Frequencies. A window will appear.
  2. Throw in the continuous variable.
    • Check 'Display frequency tables.
    • Click 'Statistics'.
  3. In the 'Central Tendency' section, check for the mean score.
    • Note: It actually depends on how will you categorize this variable.
    • For this example, we will use the mean.
    • Other literature, use the median score.
  4. In the 'Output', go to the 'Frequencies' section and then take note of the mean.

B. Recode into Different Variable
  1. Go to 'Transform' -- Recode into Different Variables.
  2. Throw in the continuous variable.
    • In the 'Output Variable' section, fill in the name and label.
    • In the example, I named it 'AgeCat' to mean the knowledge category.
    • Click 'Change'.
    • Click 'Old and New Values', and a window will appear.
  3. Assign new values.
    • In the 'Old Value' section. Choose 'Range, value through HIGHEST'.
      • Input the mean Age.
      • In the 'New Value' section, set the value as 1. 
      • Click 'Add'.
      • The result will appear in the 'Old --> New' section.
    • Go back to the 'Old Value Section'. This time, choose 'All Other Values'.
      • In the 'New Value' section, set the value as 2. 
      • Click 'Add'.
      • The result will appear in the 'Old --> New' section.
    • Click 'Continue'.
  4. Check in the 'Variable View' if a new variable is added.
    • Change the measurement level into 'scale'.
  5. Set the 'Value Labels' base on your category.

C. Check for the Frequency (Optional)
  1. Go to 'Analyze' -- Descriptive Statistics -- Frequencies. 
    • A window will appear.
    • Throw in the newly-created categorical variable.
    • Check 'Display frequency tables.
  2. In the 'Output', go to the 'Frequencies' section.
    • You will see the percentage distribution of each category you created.

Hope this helps. :)


King Mongkut's Institute of Technology Ladkrabang

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