What type of regression line does the option 'i=rl' represent in a plot?

The representation 'i=rl' indicates a linear regression line in a plot. This syntax suggests that the relationship between the independent variable and the dependent variable is modeled as a straight line, which is characteristic of linear regression. Such a model assumes a constant rate of change, suggesting that for every unit increase in the independent variable, the dependent variable changes by a constant amount.

In contrast, quadratic regression would have a term that incorporates the square of the independent variable, indicating a parabolic relationship rather than a straight line. Cubic regression includes a term for the cube of the independent variable, reflecting a more complex relationship with potential inflections. Polynomial regression encompasses both quadratic and cubic forms and higher orders, showing a more complex or non-linear relationship.

Thus, 'i=rl' specifically denotes that a linear relationship is being explored, making it the defining characteristic of a linear regression line.