Day 26: Statistics for Business Applications

• Last Time: Testing the difference in two proportions

• Collect homework 13.4 (and any stragglers of 13.1)

• Return 13.1

• 13.6 will be due at the time of your exam next Thursday.

• Questions about old stuff?
  • Difference in proportions
    • M & Ms
      • Did your proportion of browns differ from the 30% expected? (alpha=.05)
      • Is there evidence that different bags had different proportions of browns?

• Today:

  • Introduction to linear regression: "...to predict the value of one variable on the basis of other variables."
    • How well does homework predict test grade?

    • Which Honda Odyssey to buy?

    • Example: 18.8, p. 614

    • What's going on? How does linear regression work?
      • Do scatter plots indicate a linear relationship?
      • "Correlation" measures a linear relationship.
      • How do we find a "best-fit" line?
      • How good is that line?

• Next time: Regression (Section 18.1-3)

Links:

• A nice on-line course about regression