The treatment in the Results section is the independent variable. It has two levels (groups). One is Experimental and the other is Control. Even though the Results section doesn’t state it explicitly, there are 6 participants per group for a total N=12. The independent variable is typically described as the variable manipulated by the experimenter and is typically identified as the cause in the cause-and-effect relationship- a common assumption in a design looking for group differences. Under most circumstances, it considered a nominal variable and must be coded as such when defining variables in SPSS. See the SPSS Tutorial for instructions on defining variables. In addition to defining the independent variable as a nominal variable, it is helpful to identify the fixed values of the independent variable. These values will be used to identify the levels or conditions of the independent variable. See defining variables for instructions on assigning values to the independent variable.