Statistics 101: Continuous random variables

• Administrivia:
  • Exam monday Evening in Nursing Education Auditorium
  • Additional office hours before midterm.
    • (TH 11-5, F 11-5, M 10-1)
    • See homepage for details

  • I'll be out of town Thursday and most of Friday

Continuous RV's

• Densities
  • Example: Everyone make a random 3 digit number between zero and one
  • Should be evenly spread (draw picture) (1 between zero and one, 0 elsewhere)
  • 3rd digit should be evenly spread (check against class)
  • Used in scientific fraud detection
  • Compute P(.2 < X < .5), (check against class)

• Expectation and variance
  E(X) = integral(x f(x) dx)
  • variance = integral((x - E(X))^2 f(x) dx)
  • compute it for the uniform distribution above (E(X) = .5, Var(X) = 1/12)

• Example: lightbulb f(t) dt = (1/µ)e^-t/µ dt