Question

. ________Which is TRUE? i. A clear curve in the residual plot indicates that a linear model is not a good fit. ii. A random scatter in a residual plot indicates a linear model is a good fit. iii. A residual is the predicted value minus the actual value. (A) i only (B) ii only (C) i and ii only (D) i, ii and iii

Answer 1

The difference between the observed value of the dependent variable (y) and the predicted value (ŷ) is called the residual (e).

A residual plot is a graph that shows the residuals on the vertical axis and the independent variable on the horizontal axis. If the points in a residual plot are randomly dispersed around the horizontal axis, a linear regression model is appropriate for the data; otherwise, a nonlinear model is more appropriate.

When a pattern is observed in a residual plot, a linear regression models is probably not appropriate for the data.

A random scatter in a residual plot indicates a good fit for a linear model.

Appropriate linear model: when plots are randomly placed, above and below x-axis (y = 0).

Appropriate non-linear model: when plots follow a pattern, resembling a curve.

The correct option is

(C) i and ii only