Poisson Probability

 

Finding Individual Probabilities (P(X=x))

  1. Let’s suppose that I am trying to find the probability that a X=5 when you have a Poisson (lambda=6.5).
  2. First enter X into a column.
  3. Go to Calc,  Probability Distributions,  Poisson.
  4. The screen below will appear.


  1. Notice that I have entered 6.5 for lambda, which is the mean of the Poisson.
  2. If you do not enter a column into the Optional Storage blank, Minitab will display the answer in the session window.

 

             Probability Density Function

 

        Poisson with mean = 6.5

 

           x  P( X = x )

           5    0.145369

 

 

 

Finding the Cumulative Probability

  1. Let’s suppose that I am trying to find the probability that a X<=5 when you have a Poisson (lambda=6.5).
  2. First enter X into a column.
  3. Go to Cal, Probability Distributions, Poisson.
  4. The screen below will appear.

  1. Notice that I have entered 6.5 for lambda, which is the mean of the Poisson.
  2. If you do not enter a column into the Optional Storage blank, Minitab will display the answer in the session window.

 

    Cumulative Distribution Function

 

   Poisson with mean = 6.5

 

     x  P( X <= x )

     5     0.369041