Use fitted regression lines to illustrate the relationship between a predictor variable (x) and a response variable (y) and to evaluate whether a linear, quadratic, or cubic regression fits your data.
You are studying the relationship between a particular machine setting and the amount of energy consumed. You suspect that this relationship has curvature, but you need to confirm and document the curvature. You produce the following plots. The quadratic model appears to fit the data better than a linear model.
You can add fitted regression lines when you create a graph, such as a scatterplot or a matrix plot.
You can add fitted regression lines to an existing graph, such as a scatterplot or a matrix plot.
After you add a fitted regression line, you can edit it.