The following graph is a residual plot derived from a scatte

The following graph is a residual plot derived from a scatterplot that predicted the height of girls from their ages (in years).

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

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.

Solution

residual plot shows a curve pattern, simplying that the model is probably quadratic instead of linear.

Near 5.5, the residuals are positive, implying that y - y-hat is positive, i.e, the prediction is smaller than actual value.

(too small)