When designing a scientific experiment, scientist try to determine different variables that may cause a change to occur. In this context, the word variables could be replaced with factors, and not quantities. Why?
In this context, the term "variables" refers to the factors that can be changed or manipulated in an experiment in order to observe their impact on the outcome or results. These variables/factors can include a wide range of elements such as different treatments, conditions, settings, or inputs that are being studied or tested.
The reason why the word "variables" is used instead of "quantities" is because not all factors being studied in a scientific experiment can be represented or measured in numerical quantities. While some variables can indeed be quantified (e.g., temperature, concentration, time), there are also qualitative variables that cannot be expressed numerically (e.g., color, type of material, presence/absence of a specific component).
By using the term "variables," scientists encompass both quantitative and qualitative factors, acknowledging that any change in these elements may impact the results of the experiment.