Dear Dr. Abdel_Hady

You can use scores for this variable, for example give 1 for the first level and 2 for the second level .... and performed that from variable view page.

You can also, encode the data into classes, each class represent one level for this variable and perform this from Transform menu of SPSS, by using the following command from the menu: Recode in the same variables or use Recode into different variables

Best Regards

Many thanks DR Khaled

For more clarification this level of antibody is quantitative in nature & measured as (hypothetical data): 150. How to enter this set of data (the same variable) into SPSS?

Thank you once again