Chapter 22

Mix and Match

  1. 1. i or f

  2. 3. f or i

  3. 5. b

  4. 7. e

  5. 9. j


  • 11. False. When the variance of the errors changes, prediction intervals are likely to be too short in some cases and too long in others.

  • 13. True

  • 15. True

  • 17. False. If omitted variables contribute small, independent deviations, their net effect tends to have bell−shaped variation.

  • 19. False. The decision to exclude data should account for substantive relevance. An unusual case might be the most important data.

  • 21. False. It is easier to see changes in the variation in the plot of residuals on x.

Think About It

  • 23. The data would likely have unequal variation, with more variation among larger stores.

  • 25. The analyst failed to realize an evident lack of constant variation. ...

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