How does gas mileage depend on the [blank] of the vehicle? [Blank] could be weight, engine size, seating capacity, size (e.g. compact, sub-compact, SUV), etc. There should be multiple predictor variables included.

Submit a Research Proposal for instructor approval that includes your main variables, any control variables, how they are labeled, what your value ranges are, your specific data source, and your tentative research question.

I only need help with this part from the proposal: what your value ranges are? what information should go here? I just need to understand what the value ranges are? I just need an explanation.