# 12.50 Assumption violated For prediction intervals, an important inference assumption is a constant standard deviation s of...

## Question:

12.50 Assumption violated For prediction intervals, an important inference assumption is a constant standard deviation s of y values at different x values. In practice, the standard deviation often tends to be larger when my is larger.

**a.** Sketch a hypothetical scatterplot for which this happens, using observations on x = family income and y = amount donated to charity.

**b.** Explain why a 95% prediction interval would not work well at very small or at very large x values.

## Step by Step Answer:

**Related Book For**

## Statistics The Art And Science Of Learning From Data

**ISBN:** 9781292164878

4th Global Edition

**Authors:** Alan Agresti, Christine A. Franklin, Bernhard Klingenberg