The Poisson distribution is a discrete distribution. The Poisson distribution is quite useful when you want to estimate the probabilities of events that occur randomly in some unit of measure (e.g., the number of traffic accidents at a particular intersection per month).

Use: A way to remember when the Poisson distribution might be useful is when you hear or see the word ‘PER’. Examples of seeing or hearing the word ‘PER’:

  • Defects found in 100 feet of extruded plastic could be reworded to defects per 100 feet of extruded plastic.
  • Lost time accidents reported a month could be reworded to lost time accidents per month.
  • Bugs per megabyte of code.
  • Number of sick days per school year.

Six Sigma Terminology