Stat 101: Last day of class

• Admistrivia
  • Demonstrate "stack" and "split" on meat packing data to make data into usual single column
  • Exam is in ANNS 110 Dec 20th 4-6PM
  • extra office hours Dec 16th - 20th

Confidence intervals: T-distribution

• Example: On the last three jobs that were bid by Joe's Construction, the cost overruns were: 50%, 100%, and 150%. This gives an X-bar of 100% and a s-hat of 50%. Find a 95% confidence interval. Does it seem that Joe's Construction is cheating on their bids?

• Example: A rowing team wants to pick the 8 strongest rowers. Each is put on an "erg" machine and has her average Watts measured. Typically there is a 10 Watt difference between rowers, so it is desired to measure each rower to within 5 Watts. But the daily fluctuation has a SD of 30 watts. How many days on the erg machine must each rower do? What assumption would be violated?

Review

• Continuous random variables (uniform, exponential, normal)

• Quality control
  • be able to interpret both mean and s plots
  • recognize two sorts of problem--incorrect mean, too much variability

• central limit theory (averages are normal eventually!)

• checking normality (normal probability plots)

• confidence intervals
  • binomial
  • normal
  • t
  • sample size determination

Last modified: Wed Dec 8 09:03:09 EST 1999