Final answer:
The mental representation of an important variable on the y-axis is quantitative and more accurate.
Step-by-step explanation:
The statement is True. The mental representation of an important variable on the y-axis in a graph is quantitative and provides a more accurate representation of the data. The y-axis represents the dependent variable, which is the variable being observed or measured. By plotting quantitative data on the y-axis, we can accurately analyze and interpret the relationship between the independent and dependent variables.