Back to Assess fit by analyzing residuals — Problem 5 · Task Set 7

Exercises: Assess Fit by Analyzing Residuals

Work through each section in order. A residual is observed minus predicted: positive when the data point is ABOVE the model, negative when below. Keep the sign. When reading a residual plot, remember the key idea: random scatter around zero means a GOOD fit, while a clear pattern (a curve or a fan) means the model is wrong.

Grade 10·20 problems·~35 min·Common Core Math - HS Statistics and Probability·standard·hss-id-b-6b

Work through problems with immediate feedback

Fluency Practice

Compute residuals and read residual plots.

A residual plot shows a clear U-shaped pattern: the residuals are positive at the left and right ends and negative in the middle. What is the most likely problem, and what should you do?

The data is curved and a line was the wrong family; refit with a quadratic or exponential.

The data was recorded incorrectly and should be thrown out.

Nothing is wrong; a U-shape is the normal look of a good fit.

The residuals should be made positive to remove the pattern.