A useful residual plot should look like unstructured noise around zero, not perfect predictions. Check for balance above and below the line, then look for curves, trends, clusters, or changing spread; their absence supports the fitted functional form as a reasonable description.
Inside Gozunta
Turn the preview into practice.
More than a preview
Gozunta lets you study this problem—and more than 10,000 others.
Create targeted learning sessions, use hints, check your answer, read the walkthrough, watch the video, print the work, and track your progress.