Does the residual plot indicate that a line is a good model for predicting the height of girls from their ages? Explain.

Answer:

If you were using the regression line to predict the y-value for x = 5.5 years, would your prediction most likely be too large or too small? Explain your reasoning.

Answer:

A plot of residuals (vertical deviations from the regression line) shows the errors or lack of fit, so it would indicate a good fit if the residuals are small, vs. over fit if they are large. Due to age related growth short pre teen, and a plateau after age 21, I would expect a linear regression would offer estimate age 5.5 years.