You might want to review Workshop #1 on various data types. Please remember that your IV or DV might be of any type. Experimental conditions (IVs) might be from a numerical scale such as the dosage of a drug used to treat depression. However, the IV could be from a categorical scale when you compare two chemically different drugs to treat depression.

Be sure when using Quantitative Variables to pay attention to the difference between Discrete (limited to certain values) and Continuous Variables (falls on a continuum and is not limited to certain values).

Similarly, you could have a numerically scaled dependent variable such as reaction time or a categorically scaled dependent variable such as choice of favorite food.