Dependent and independent variables
Dependent and independent variables: the dependent variable is the outcome being explained (y-axis); the independent variable is the factor doing the explaining (x-axis), in a scatter plot or regression.
See it move
A regression fits Sales equals €2,000 plus 5 times advertising spend. Advertising spend is chosen by the business, so it is the independent variable, plotted on the horizontal axis; sales is the outcome it explains, the dependent variable, plotted on the vertical axis. At €800 of spend, predicted sales are €2,000 plus 4,000, or €6,000.
Check yourself
A researcher fits a regression of monthly revenue on monthly advertising spend for a chain of stores. The fitted line is Revenue = €12,000 + 3.2 × Advertising spend. For a store that spends €1,500 on advertising this month, what is the predicted revenue, and which variable is the independent variable?