Day 05: Statistics for Business Applications

• Last Time:
  • Review of qualities of histograms and measures of central tendency
  • Measures of spread

• Today:
  • Return homeworks:
    • Chapter 1
    • Chapter 2
    • Use complete sentences! I'm going to crack down on that from now on. We actually want to see a nice little analysis. Check your grammar, check your spelling, etc.
    • Interpret the histogram! (stats)

  • Collect Homework #3 (sections 4.1-4.2)

  • Do you have any questions about the homework associated with 4.3? (Due Next Tuesday - no homework due Thursday)

  • Chapter 4: measures of spread
    • Review
      • range
      • variance
      • standard deviation
    • There are two rules based on the standard deviation that you'll want to be aware of:
      • The empirical rule - the 68/95/99 rule.
        • The standard deviation serves as a "typical deviation"
        • Works well when the distribution is bell-shaped
        • May work okay in any event.
      • Chebysheff's Theorem - the 1-(1/k^2) rule.
        • Works all the time, but is extremely conservative: it leads to a 0/75/89 rule!

  • Chapter 8: The normal distribution and probabilities
    • Joe Six-Pack investigates beergate at Veterans Stadium Philadelphia

      Beers were being served 2 or 3 ounces short! The horror....
      Hear about it on NPR -- Minute 1:30/4:10

    • What might the beer distribution have looked like?

      Using Minitab to generate random data

      Calc -> Random Data -> Normal

    • An old story: Poincare and his bread

    • Java applet from book's CD?

    • The empirical rule - the 68/95/99 rule - comes from the normal curve

    • Probabilities and the area under the curve

• Next time:
  • No problems due
  • Finish normal distribution (the bell-shaped curve) - calculation of probabilities

Links:

• Bread, bakers, and the normal curve