Geometric Distribution (Geometric(x) where x = the chance of success)

  • Measures the chance of success after a number of events
  • f(x) = (1 - p)x - 1 p (dgeom)
  • F(X) = pgeom
  • E(x) = 1/p
  • VAR(x) = (1 - p) / p2
  • Remember in R that you need to subtract the x value by 1, as x represents the number of failures until a success instead of the number of tries to get a success

Poission Distribution (Poission(λ) where λ = the expected successes in a time frame)

  • Measures the expected number of successes in a time frame
  • f(x) = e-λλx / x! (dpois)
  • F(x) = ppois
  • E(x) = λ
  • VAR(x) = λ