Use a fitted regression line to evaluate the relationship between a predictor variable (x) and a response variable (y) and to evaluate whether a linear, quadratic, or cubic regression model fits your data.
To add or define a fitted regression line when you create a graph, click Data View. To add fitted regression lines to an existing graph, click the graph and choose . To edit fitted regression lines, select and double-click the lines that you want to edit. For more information on selecting lines, go to Select groups and single items on a graph.
You can customize the following items.
- Model Order
On the Regression
tab, select the model for the fitted regression line.
- A linear model can show a steady rate of increase or decrease in the data.
- A quadratic model (often approximately in the shape of a U or an inverted U) can explain curvature in the data.
- A cubic model can describe a "peak-and-valley" pattern in the data.
- Fit intercept
By default, Minitab includes a term for the y-intercept. Usually, you should include the intercept in the model. To fit the regression line without the y-intercept, on the Regression or Options tab, deselect Fit intercept.
- Line attributes
- On the Attributes tab, change the color, size, or type of the fitted regression lines.