1 / 14

Correlation: Problems

Correlation: Problems. SD Line. True or false: the SD line always goes through the point of averages. True or false: the SD line always goes through the point (0, 0). SD Line. SD Line. Male college students have an average height of 69 inches, with an SD of 3 inches.

lara
Download Presentation

Correlation: Problems

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Correlation: Problems

  2. SD Line • True or false: the SD line always goes through the point of averages. • True or false: the SD line always goes through the point (0, 0).

  3. SD Line

  4. SD Line • Male college students have an average height of 69 inches, with an SD of 3 inches. • Their average weight is 140 pounds with an SD of 20 pounds. • The correlation between height and weight is 0.6. • If one of these students is 72 inches tall, how heavy would he have to be to fall on the SD line?

  5. Husbands and Wives • A study of the IQs of husbands and wives obtained the following results: for husbands, average IQ = 100, SD = 15, for wives, average IQ = 100, SD = 15. correlation coefficient r = 0.6.

  6. Pick the Scatter Diagram

  7. Heights • Suppose men always married women who were exactly 8% shorter. What would the correlation between their heights be? • Is the correlation between the heights of husbands and wives in the U.S. around –0.9, -0.3, 0.3, or 0.9?

  8. Gasoline Economy • For a representative sample of cars, would the correlation between the age of the car and its gasoline economy (miles per gallon) be positive or negative? • The correlation between gasoline economy and income of the owner turns out to be positive. How do you account for this positive association?

  9. Grade Point Averages • Three data sets are collected, and the correlation coefficient is computed in each case. The variables are: • GPA in freshman and sophomore year. • GPA in freshman and senior year. • Pick a likely value for the correlation coefficient: -0.50, 0.0, 0.30, 0.60, 0.95.

  10. Homework, Midterm, Final • In one class, the correlation between scores on the final and on the midterm was 0.50, while the correlation between the scores on the final on the homework was 0.25. • True or false, and explain: the relationship between the final scores and the midterm scores is twice as linear as the relationship between the final scores and the homework scores.

  11. Human Growth • A longitudinal study of human growth has been under way since 1929. The scatter diagram shows the height of 64 boys, measured at age 4 and 18. • The average height at age 4 is around: 38, 42, 44 inches. • The SD of height at 18 is around: 0.5, 1.0, 2.5 inches. • The correlation coefficient is around: 0.50, 0.80, 0.95. • Which is the SD line: solid or dashed?

  12. Comparing IQ Test • In a large psychology study, each subject took two IQ test. • You are trying to predict the score on form M from the score on form L. • On the whole, will the prediction error be smaller when the score on form L is 75, or 125? Or is it about the same for both?

More Related