Probability Distributions

Probability Distributions

1. Rectangular Distributions

   • Called uniform distributions
   • Good choice when the upper and lower limits are known and there is very little or no further information about the distribution
   • Can be discrete or continuous

2. Triangular Distributions

   • Best choice when you are given information about the upper limit, lower limit and the mode. You are given little or no information about the shape of the distribution

3. Binomial Distributions

   • Only has two outcomes
   • There are a fixed number, n, of IDENTICAL trials
   • Each trial is INDEPENDENT
   • The probability of success 'p' at each trial is consistent
   • Are discrete

4. Poisson Distributions

   • Events occur independently
   • Events occur at random
   • Events cannot occur simultaneously or in the same place
   • Mean is proportional to the size of the interval
   • Discrete events over a continuous interval
   • Inverse Poisson
     • Sometimes we need to calculate λ when we know the probability that no events occur. We do this by substituting P(X=0) into the formula
     • Note: P(X=0) = 1-P (one or more events occur)

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